I would hope no one on this forum would get on anyone's case for using a government program that they need. You have a diagnosed medical condition and a child: you need the SSI, I think that's pretty simple.
Without specifics, it's hard to give you advice on your budget, although you can absolutely get that cell phone bill down by half or more with Ting, Republic or a pay as you go plan. You also list a rec center fee and allowance, presumably for your son. Is the rec center necessary for your condition? If not, it needs to go until you're on a better track financially. For exercise run, walk, bike, go to the local high school and run the bleachers, do all of these things on your way to the places you normally go in the car. Maybe even sell the car and get a bike and bus pass. The allowance: how old is your son, how much is the allowance? If we're talking a quarter a week for a 4 year old, that can stay. If it's more, you two may need to have a frank conversation about your financial situation and figure out a compromise. Say, if the allowance is $10 per week, he can keep it but he is responsible for buying half his own clothes.
My other big question would be, is your condition that makes it impossible for you to finish school as well managed and under control as possible? If not, what would it take to get it under control and maybe try school again. Hopefully in each of your 4 tries, you've been collecting at least a few college credits. Are you close to a Bachelor's degree? An Associate's degree? Maybe with better control of your condition you could finish some kind of degree or certification, bringing up your earning potential. I am fortunate enough to have no experience with SSI so I can't speak to how to dovetail from SSI to gainful employment but it seems like it should be possible with careful planning.