Help... disabled, need to lose weight.

I'm 31 years old, I'm physically disabled, and I need to lose 100 pounds. The problem is, being disabled, I'm not able to work out or exercise. And I have discovered my metabolism is extremely low. Eating 1200 cal is the minimum you should eat before your body thinks it's starving itself. But at 1200 cal a day I maintain my current weight. Does anyone have any idea that might boost my metabolism? I do physical therapy in the pool once to twice a week, but I don't have a reliable ride to get there any more frequently than that. I just feel so stuck!