You have to step back and think clearly about these issues...the weight gain is a secondary issue, since the world is divided between those who eat more when depressed and those who lose their appetite. You seem to be the later, so the way to gain weight is to master your depression, and at your age, drugs alone may not be enough...you will have to get your life going on a good track, and that might require counseling, and when that happens, your appetite will come back...take care of your life.