Tell your parents or another trusted adult just what you said here. At 5'6" and 122 lbs you don't have a weight problem. You say you don't have time to exercise. Is there a sports team in school that you could join? Is there a safe park near you that you and some friends could hike at on the weekends? Do you have a dog that needs to be walked a couple times a day or does someone elderly/disabled in the neighborhood have one that you could walk for them? Please don't keep this to yourself. The fact that you admitted that you're starting to worry about this is the first step. Go grocery shopping with your mom and help her pick out a lot of veggies or other healthy foods that you like and help her cook them at home. Everytime you want to pig out, have one cookie (instead of ten) and get out of the kitchen. Clean your room, call a friends, take a long bath. Look on the net for some chat rooms/support groups that deal with eating disorders. Your local hospital probably has a support group too.