Okay, you say that you live in a kitchenette now. Last year you lived at home with your mom and complained about the food she cooked for you. Now, you are in your own place. That is great. SSI is such a small amount of money. After your rent and utilities, I would assume that what is left is so miniscule that you would easily qualify for foodstamps. If you start receiving them, and start using them to buy your food, she could not complain about you spending money on food, because you would not be spending money on food.
SSI will leave you with no money beyond bare bones survival. Have you considered joining 'ticket to Work? They will help train you for a job, find you a job, and many even teach budgeting and basic life skills. Then, if you do well, they could be an allie in helping you to regain your freedom. If you can work, but not full-time [nothing to be ashamed of] maybe a little off the book walking dogs, cleaning dog poop, aerating and mowing lawns. These could give you extra money. You could stash it away for your future. Money buys options.
Also, I believe that you can request that someone else be in charge of your payments, even social security can appoint a representative. If the financial responsibility is not an issue between the 2 of you, maybe you can restore your relationship with your mom.