Oh, the hazards of weight gain from psychotropic meds. I am sorry you have gained so much weight from the Seroquel. Glad you are weaning off it.
There are currently some FDA approved drugs for weight loss but most of then have side effects so you would have to look at that carefully before diving in. I wonder if you might revisit what you diet was when you lost weight and maybe copy that. That was part of the equation so at least implementing that part would probably help. Too bad you are unable to exercise because boosting your metabolism that way instead of using a stimulant would be safer. If you can get some of the weight off through diet, it might become easier to begin a walking or exercise program.
Getting started is always the hardest part. Maybe a coach or an app for your phone would be helpful. I hope you find something that works for you.