When you have devils sight does that mean that you can cast darkness on your self and still fight without penalty's that you might normally have when in the darkness spell? Because i have a Artaficer/Worlock humen variant build and i was wondering if i would have the same ability as a shadow sorcerer does to fight inside my own darkness i was told by my wife that it depends on the DM is she right?

Darkness creates magical darkness, devil's sight lets you see in magical darkness. 

Devil’s Sight

 You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet.

You can see in your own darkness spell, per the ability description. And anyone else's darkness spell too.

So that would make you a real threat to a shadow sorcerer then if you can see in to his darkness spell as well he might think he is safe but you could attack with no penalty's and so some real damage

correct. The invocation vision is more powerful than the shadow sorc vision.

This is the player character that i made take a look and tell me what you think 

https://ddb.ac/characters/35012795/z74EfL