I'd say, you don't need to worry too much about your weight. That's a good thing!
But, I would also say, going to the gym is a good idea--it always helps to stay fit, and will help you not to put on any extra pounds. And, cutting out fast foods and eating better quality foods will definitely help. I think if you did those two things, you'd see a couple of pounds drop off in the next month.
Check out the Calorie Counters forum and some of the other programs on 3FC.
Sorry to hear about your living situation--how do you get to school? Gosh... It must be hard to cope with having such an unstable home life.
Hang in there!