I've actually heard that you can gain weight because of starvation mode. You might want to try actually adding calories to activate your metabolism, I've heard it can actually cause you to loose the weight! Your body might be afraid of you "starving" so it's hoarding reserves. Maybe 50-100 extra calories a day around breakfast?
I am by no means an expert so take what I suggest with a grain of salt, its just something I read. Hopefully someone more knowledgeable can either confirm or deny what I've said. My mother had an eating disorder and it really messed with her metabolism, it was the cause of her weight gain after dieting, which is partially what I'm basing my suggestion on. She really messed up her system though, so its hard for her to do anything
I don't think your metabolism is that far gone though at all, so don't be afraid.