I have recently fallen in love with the game of D&D. I participated with a group for a small story line and began to create a campaign of my own when I was stationed overseas. I have now moved away from my group and want to start up again. 

I am fascinated with a sorcerer of Wild Magic. I love the spontaneous features of the class origin.

I am having trouble, however, creating a character with a great back story and not just following the orphaned cliche. Something with real depth.

Any Ideas would be much appreciated!!

I recently made a character of this style myself. Back story for a Wild Magic user should start, in my opinion, on how the magic was viewed by your upbringing. You could have had a very understanding, supportive group of family/tutors that taught you that the benefits of your magic out way the strange side effects (check out the Harpell family in Longsaddle if you are into the d&d lore). This creates a self-confident character, who may not sweat the odd situations your character can put a party into. Conversely, say your magic was seen as dangerous from birth. Perhaps a surge brought some catastrophe upon your family or town. This is the path I took. The character I made agonizes over mistakes, both magical and social, forever desperately trying to appear normal. Playing into both of these back stories, give yourself an odd physical quirk that relates to your power origin. Have your eyes change color with the seasons (feywilds), a mark on your neck which only appears when you are warm (fire planar), or maybe have dark purple veins on one palm (shadowfell). This Mark will be flaunted, or hidden, depending on which path you choose.

I know that I may be late to this topic, but I did play a Kobold Sorcerer a while back. His name was Jester and his entire arc was that he accidentally turned a noble into a sea shell via a polymorph spell (I know that you can only turn creatures into animals, but this is an exception). He wears a little Jester's hat and wears a light blue cloak with a gold-rimmed collar and sleeves. He is more on the Chaotic Neutral side. Idk, I had a lot of fun with him when I played him.

The fun thing about sorcerers (and warlocks, to an extent), is that when you're deciding on their origins, those classes lend themselves to a "Superhero Origin Story" kind of telling. Just because your sorcerous powers depend on your bloodline, it's up to you to say just how all that funky magic stuff got all up in your blood to begin with. It doesn't have to just be from one of your ancestors. Maybe you were the unwilling experiment of a mad artificer who spliced wild magic into you? Maybe you were struck by lightning in the middle of a freak storm at sea and woke up stranded on a deserted island with strange new powers? Maybe after a near death experience that you miraculously survived, weird things started to happen to you that you eventually learned to control? 

If this is one of your first times making a sorcerer, ask yourself if there are any superhero origins that you might want to take inspiration from?  Stealing from stuff you like and tweaking it to fit the setting, or combining elements of things you like to create something new, are completely valid ways to play the game. 

Mine is the (unwilling) keeper of the Book of Random Knowledge.

Back story can depend on world setting. I don’t really know the others but in the Forgotten Realms it’s less than 10 years since the end of the spellplague and the return of Mystra and “normal” magic.. the spellplague and it’s plague lands and wild magic areas are fading but still around so exposure to ne accidentally or on purpose could have activated a latent talent. While lots of folks seem to go for the cringy or edgy backstories for “good roleplay” reasons I don’t. So there is no reason it can’t be a fairly normal background - maybe they were a soldier and caravan guard and got exposed on assignment or on duty protecting a caravan (or raiding a bandit camp after defeating their raid). Have you considered a nonhuman character? That can open up other possible origin stories as well. I would start with a race and background selection then build it up from there. Wild magic is fairy easy as exposure to a wild magic area or simply something that activates a latent talent that he is never fully in control of suffices to explain the sorcerous talent. I would also look at the UA1 origin and backgrounds and possibly build off that.

I mean a wild magic sorcerer could literally be anything. One fun one I’ve seen played was a normal girl who grew up in a cult that hated magic. She had to hide and try and get rid of her powers but her magic has other ideas. 
it all depends on what flavor you want to make it. I liked the idea of making the magic almost have a mind of its own, but that’s just me

I'm not a huge fan of elaborate backstories. Most of it is useless. First of all, if you're doing backstory without your DM, there's a good (almost certain) chance it's not going to pertain to the adventure or get used. 

It's like receiving long and detailed text messages from someone who has the wrong number...

It isn't to say a back story isn't helpful or worthwhile to get the feel of the character, which can then be expanded upon and incorporated in to the story.

I have a wild magic gnome sorcerer whom I think is just going to be old and his powers just decided to manifest at an older age .....

My favorite part of wild magic sorcerers is that there magic is inherently chaotic and doesn’t really need an origin. Imagine a peasant baby who suddenly develops unstable magic powers for no discernible reason, scaring the daylights out of there parental units.

I played a half-drow Wild Mage, his mother was a Matron from beneath Dambrath, a region where the drow had conquered part of the surface lands and used half-drow nobles called Crin'ti to administer the territory (although as a male he would still be limited to a very low position). 

Originally trained in diplomacy, when his arcane abilities manifested he was apprenticed to a wizard, who hated him and called him 'a burr on the weave' -- as a sorcerer he didn't study, he just tried to imitate what his teachers did, with occasionally unpredictable mishaps.  He became an adventurer by necessity after a Wild Magic surge teleported him to Undermountain. 

I played him as pretty confident in "ray" spells that just required pointing at a target, but more likely to mess up new spells or ones with complicated gestures and words.

One I like that I find can be fun, though I am sure some people would find it to unlikely to happen or elaborate to be anything but cringy, is the idea of a character who got a wish from a genie or other wish granting creature, and wished for either magic, power, or a way to help people out. But the magic is unstable and is being drawn from another creature, who can somewhat influence the wild magic, but not entirely. You can take it in just about any direction from there, but it needs dm permission for sure, plus a bit of homebrewing.

Someone who wanted to be a wizard, but encountered a wild magic source that gave them magical power, but also removed their ability to comprehend writing.