Losing muscle like crazy--what's going on?

I'm a 22 yr old male who recently started recovering from bulimia this past year. After putting on 30 lbs during recovery, my weight has finally started to stabilize around 150 lbs. Needless to say, I kind of look like a wreck from everything that happened. I've tried to start eating properly and running and working out again, and my weight has slowly started going down to its normal range, but it looks like I'm looking even heavier than normal. The only thing is is that my body seems a lot firmer and there is almost no flab left anymore, but I seem to be losing more definition and muscle tone every week. Like I said, I've been eating and exercising more properly this time, but I'm not looking any leaner--can anyone tell me what's going on?