I've been playing in a campaign for about 6 months now, from lvl1 to lvl6 and done enough combat that if it was XP instead of milestone we would be close to lvl8 by now.  
Is it normal that my group has only received about 300gp, a +1 longsword, a shield with radiant resistance, a whip(it has an effect but dont recall it) and a few unmissable pieces of gear(amulets given to players by gods that give speak with animals at will etc).  
In terms of CR, we've taken down encounters that would be about CR 12 multiple times as a group of 5, including an Orc that hit our fighter for 60 damage when we were lvl4.  
We've saved a town from a tyrant king, saved a temple from an assault by the BBEG, liberated a small armys worth of goblins, fought(and killed a couple) essentially generals of the evil angel BBEG.
  
Am I expecting too much? based on the PHB/DMG, skilled workers are paid about 2gp a day, but this is like a world ending level campaign where things like god killer blades are brought up and gods dying. I feel like at the very least we should be earning enough to be able to get the whole group a +1 weapon each by now, and a few health potions.  
  
EDIT: Forgot to add, initially id been asking to check for loot constantly when exploring but had been finding nothing, then started getting asked to roll for perception just to find basic, large loot like a sword... as if that could be missed.

Loot is very campaign dependent. Mathematically, you can still be effective with no magical gear, as it seems you are finding. Martials can run into problems with enemies with resistance, and some plate mail for the heavy armor types is nice, but not required. Granted, it’s much tougher without magical loot, but still possible. At least until you start getting to things like Tiamat or the tarrasque , which are immune to non magical damage. But almost no one plays at those levels.

That said, magic items are cool, and I get wanting more. You should talk with your group about it. Could be the DM has a plan, could be they’re not realizing they’re being a bit stingy. 
One thing I will say, is doing it this way has its own up sides. I bet the +1 sword feels really special. 

I'm playing a Circle of Stars Druid and have been doing most of the damage every encounter, despite wanting to play supportive. Unfortunately the rest of the party is very "suboptimal" in how they've built their characters and picked their multiclass/feat/asi etc, so I've been sticking out every fight and I think perhaps the DM has been intentionally making fights harder as a result, which has meant I cant relax in combat and have to try hard a bit if I want our party to live without the DM needing to fudge half the rolls(our fighter has a +5 to hit, is still only in Chain Mail and has less hp than me despite having a better hit dice).  
  
So really, I'm not struggling at all, but our martials are getting to do less and less every combat session.  
Regarding the +1 sword, only the fighter could use it but their whole character is centered around their dual scimitars so it got sold... for 80gp.  
When I complain about this, it's definitely not for me. While it'd be nice to have some new things to play with, I'd also like to actually play the role I wanted to, but because I'm the highest threat and the tankiest member of the team, I end up needing to focus on damage because otherwise combat goes on for 7+ rounds.

In the campaign I currently play we recently received our first magical weapon, a +1 longsword. This went to my chcaracter (Hexblade) who is the only one who can use such a a weapon, although he has yet to do so (the only time he has used a longsword was once when casting green flame blade to kill two bandits, in one attack). The other magical items we have are a bag of holding, an elven cloak and a rope of climbing. We are level 7

Who cares about magic items? We succeed without them

This is just how some DMs are. I don't know if it's "normal," but it's not uncommon. Some are afraid that magic items will make the characters too powerful. Some want magic items to be rare and special (although selling one for 80gp makes me think your DM is not in this category). Some prioritize loot last in all the things they have to do and just never actually get to it before game day.

I have one game at level 8 with more items than I can fit in my attunement slots, and I have another at level 12 in which my only magic item is a melee-focused staff that I never use because I'm a wizard. I'm glad I get to play in both kinds of games, but as a player I like to have toys. And as a DM, I like to give them out.

 Loot management varies heavily by the DM and campaign. I would say what you describe is lower than average, but not exceptionally low.

It could also just be your play style doesn’t mesh with this group. I mean, for a fighter to be +5 at level 6 seems like they either don’t quite understand how to build a character, or they do, but they are making choices they find interesting in a different way. Neither of your versions of the game are right or wrong, you just seem to want different things. Have an out of character discussion with the table about it. Either you can meet halfway as a group, or if you can’t, maybe your better off finding a different group. 

Session zero. Could be that the DM wants a low magic campaign and you didn't know that up front. Better to learn things before you start, so you can either prepare for the eventualities or so you can leave and find a game to suit you better. 

So, your Fighter has either a Str or a Dex of 14 or 15 (and the other is at best the same or lower) at L6 after having had two ASIs?

That's a lot of interesting decisions that they've made.

Quote from KesslerCOIL >>

I'm playing a Circle of Stars Druid and have been doing most of the damage every encounter, despite wanting to play supportive. Unfortunately the rest of the party is very "suboptimal" in how they've built their characters and picked their multiclass/feat/asi etc, so I've been sticking out every fight and I think perhaps the DM has been intentionally making fights harder as a result, which has meant I cant relax in combat and have to try hard a bit if I want our party to live without the DM needing to fudge half the rolls(our fighter has a +5 to hit, is still only in Chain Mail and has less hp than me despite having a better hit dice). 

Ah, therein lies the problem. It's not about the DM being stingy with loot, it's a communication issue. If your fellow players feel like they're not having fun for any reason, they should be letting the DM know, and the DM, in turn, should work to fix the problem. Or, maybe your group just isn't that into combat in general, in which case there should be more communication there to make sure everyone's on the same page. Perhaps some participants should be switching to different groups if they feel like their playstyle isn't jiving with everyone else's.

If the Dungeon Master had a magic item sold for only gold pieces, then money is either intentionally worth more in this world than in comparison to other ones in at least some areas (which might explain the smaller amounts of loot), or they haven't done enough research on how much things should be sold for.

The amount of coins you have is unusually though, but this varies a ton by campaigns and worlds and wanting less magic or less abundantly rich players is a perfectly valid goal that a DM might seek.

All in all, i would like to echo the excellent advice of CoolerAid: If this is a problem for you, politely talk to the DM about it because they can't change something you don't like if they have no idea that you're against it. Additionally, if it ruins the game experience and the person in charge of your group says no, then you are not obliged to stay at that table.

PS. I would ask your DM why you would have to roll perception to see a sword, because your passive score should have you covered there unless the sword is camouflaged or something.

I don't, as things go, give out very many magic items to my players because that just sort of 'feels right' to me as a DM and my style. I do give out things here and there, but they are usually trinkets or magic items that aren't combat focused because my players always seem to come up with some cool ideas for using them to solve problems and get out of jams that I would not have expected/predicted, and I enjoy seeing that. Part of my approach is that the characters themselves are heroic and aren't dependent on magic items to be extraordinary. That said, I'm usually running things at first or second tier, if I got into third or fourth tier, I would definitely be giving out more armor, weapons, etc.

Having DMed for dozens of people across many groups, I've only ever had one person express dissatisfaction about it. As mentioned above, it's really a DM style thing (although your DM may be willing to change it up if you talk to them about it and it works for the campaign, etc.)

Remember your lifestyle expenses.
30 gold a month is a modest lifestyle for most everyone.

Realistic roll play could be what your DM is looking for. In any case its not bad. Its just different.

I have played the Monty Hall campaigns and they get boring fast.

The amount of magic items isn’t bad. Would do some more gold though. Maybe throw in some gems and art pieces so you could do a little mini quest thing to find a buyer. 

Quote from optimistic14 >>

The amount of magic items isn’t bad. Would do some more gold though. Maybe throw in some gems and art pieces so you could do a little mini quest thing to find a buyer. 

 yeah, the monetary reward is what sticks out to me. but maybe there's just not been a lot of use for it. players might not be voicing their desires for things like armor upgrades, healing potions, and trinket peddlers. time for a little out of character roundtable discussion before the next session.

Here is what the DMG says bout starting at higher levels, that can also be a decent guide to how much you could e gaining indifferent style campaigns:

Starting at Higher Level

Experienced players familiar with the capabilities of the character classes and impatient for more significant adventures might welcome the idea of starting a campaign with characters above 1st level. Creating a higher-level character uses the same character creation steps outlined in the Player’s Handbook. Such a character has more hit points, class features, and spells, and probably starts with better equipment.

Starting equipment for characters above 1st level is entirely at your discretion, since you give out treasure at your own pace. That said, you can use the Starting Equipment table as a guide.

I would and definitely do give out more loot than that, and the default assumptions from Xanathar's for example would put you at maybe 20ish magic items so far for level 6 (including consumables like potions of healing) BUUUUUT as others have said, it is entirely campaign dependent. I can easily see an interesting campaign with far less loot than I normally grant.

So, bottom line, like others have said - and is what the vast majority of issues boil down to - it is likely more of a communication issue than specifically about loot. Low loot campaigns are fine and can be plenty of fun, so if one isn't fun, it is likely not because of the loot levels, but something else. Your follow up message seems to get to more of the heart of the issues you are facing, and they really aren't necessarily about the amount of loot. That might be exacerbating the problem, but it's not the actual problem itself.

The most important thing the DM needs to do is try to keep things balanced - for example, if the game is centred around flying monsters or incorporeal ones, trying to get some items in fairly quickly to give the melee guys something to throw or magical weapons (even if they don't have +1 or anything) which give them a chance to deal damage. Similarly, if the game features very fast melee monsters who are drawn to magical beings, then they might consider some loot going in that's themed toward the magic casters.

One thing to consider is that if you're doing the levels of research it sounds like you are, then you are risking making them feel pretty bad. It's one thing to say "I would like to find some more loot, my character will be looking out for quests or rumours which may end in magical items and gold!", and it's entirely another to say "I have been auditing your DMing style, based on the XP we gained from the monsters which I have been looking up we should be 2 levels higher than this, and based on the guides in the DMG we should have more magical items..." and so on. One is dropping an in-no-way-subtle hint, and the other is accusatory and will feel bad.

I would recommend talking to the DM and saying something like:

"Hey, I'm really loving the campaign at the moment, can't wait to see where it goes next! I was thinking, my character is probably going to be looking to start accumulating some more wealth soon, maybe some magic items, so I thought I'd let you know so that you can consider them for the future! They'll be looking for quests, listening for rumours, that sort of thing. >Character< has probably noticed that >fighter< is attached to their sabres so may be on the lookout for something like enchanted gauntlets or something which will give them a magical edge without making them swap out their weapons!"

DMs love it if you give them inspiration and ideas, and dislike it if you give them specific requests. I know for a fact that I have only once agreed to a specific request, and that was because the character had missed all the loot I had laid out for them in the previous room, and they said "Do I happen to see any magical weapons suitable for a monk anywhere in this armoury we're looting, like a sun blade?", and I had prepared stuff for the barbarian in that room, and the player had been telling me how cool sun blades were and I had neglected t otake the hint.

Saying "I might be looking out for something to help the fighter in combat" is much better for the DM than "I would like a homebrew item which is a pair of gauntlets which give +1 to attack and damage rolls if you are dual wielding, and makes the attacks magical". The first nudges their imagination in a way you hope to enjoy in the campaign, and the other is telling them you have already decided what should be waiting for you in the world! It also leaves the future a mystery for you, which is good!

Quote from Linklite >>

So, your Fighter has either a Str or a Dex of 14 or 15 (and the other is at best the same or lower) at L6 after having had two ASIs?

That's a lot of interesting decisions that they've made.

 15 dex/13 str wearing Chain Mail

Quote from optimistic14 >>

The amount of magic items isn’t bad. Would do some more gold though. Maybe throw in some gems and art pieces so you could do a little mini quest thing to find a buyer. 

 Yeah we've been getting some things to sell, but typically things are selling for about 1/3 of the original value at best, so if we found an Emerald(1,000gp value) it'd sell for around 300gp with a persuasion check.