I think you have a cute art style and I like the general idea of the character, but I'm personally not feeling the sort of all over the place color scheme on the character, like with the heterochromia on the irises, the clothing being differently colored on different halves of the character, etc.
I suppose you could call it a matter of taste, but personally I believe even with a more simple color scheme and a more uniformly designed outfit, the character could be conveyed well enough. For example, you already have one of the straps of the overalls down, I think that alone is sufficient to convey the character as "messy" in terms of her dress, or unstable or perhaps childlike in terms of her mental state, or what have you. As it is, it just feels like there's a bit too much going on in a way that doesn't really add a whole lot to it.
All that said though, I do dig that you gave a backstory for the character and you seem to have put a lot of thought into it. Keep it up and I'm sure you'll do something nice with both this character and your future characters.
