https://en.m.wikipedia.org/wiki/Supernormal_stimulus

I know the solution is to see a dietation, and only stock my home with healthy foods and go to the gym maybe but the truth is I can’t really afford that

You don’t need a dietician to do the second part and you don’t need a gym membership to work out.

I was 210 pounds a few months ago. Now I’m 190 pounds. All I’ve changed is eating less fast food. If you’re otherwise healthy it really is as simple as reducing calories.

If your mom is otherwise supportive, you should just tell her that you need to change your diet, both for your physical and mental health. If she doesn’t respect that, you should, if it’s safe, apply pressure.