Your post sounds really disordered. You shouldn't be looking to loose weight! Your caregivers are more than able to life manage, and it is just an excuse you are using to justify starving yourself. And 800 calories is way to low, regardless of wether you are in a wheel chair or not. Please seek some help!
So please go to the doctor and ask? I'm sure he/she will be able to tell you the correct calories you should be consuming and if you should even lose weight. (:
I'm sure an extra 15 lbs isn't that much on your caregivers. Rather than doing low carb diet, I try to go for low glycemic index diet. So basicallly I cut out as much junk food as possible, try not to eat out, eat tons of fruits for snack. LOL I haven't touched potato chips in years nor have I touched soda. I'm around the same weight as you are but 5'7" probably have a much smaller frame than you. Caloric intake is just under 2000 kcal a day. I guess losing 15 lbs wouldn't hurt, but you're already at a healthy weight.