Is this my fault?

This is question may be a bit emotional, and I’m not big on drama in general either, so just a forewarning. I have been wanting to ask this for a while now, but did not know how to word it, so here is my best job:

I realized not too long ago that my mother may not have really done much for me to support me, and I am not quite sure if it is my fault or if it is hers. Since I was young, I remember my doctor saying that I should eat more and am very underweight. I used to always think that it was my fault, and even my mother said that I was a picky eater. But now when I look back on it, I do recall not wanting to eat many things made, but then I also remember there consistently not being an actual meal to come home to. I can remember various days where the only food that I would eat was Ramen Noodles or a frozen meal or something similar.

Though these memories are a bit vague and there for possibly inaccurate, I feel that I can justify them by observing how my mother only cooks once or never during a week nowadays, which made me question whether or not I was truly the problem. Her dinners consist of Cheetos and similar chip things or a potato or canned soup or something similar. I asked her why she doesn’t cook for me and she said that she “gave up on me” because I was so picky and had an “eating disorder” (her words).
Ever since about two years ago, I have been responsible for myself mostly, especially when it comes to food, which I have focused most on in this thread. I don’t pay taxes, but I drive myself everywhere, buy my own groceries (with my own money) and cook my own food. It has lead to me having a terrible relationship with my mother.

I will say again that I do recall being a picky eater and that my dad cooks for me occasionally when he is home, but I look at my brother who is in his mid-early 20s and weighs 133lbs (he is about 5’10”) and it again makes me question if I really was the problem. I have gained a little bit of weight since I started depending on myself, but it took me a while to actually realize the amount of food and calories that I should eat in one day (and took me time to gain a bigger appetite).
In the end, am I to blame or is she? Is she responsible for me? Should she have really “given up” on me?