Katie,
My son who is the same age had a brain tumor removed as well, his weigh has gone up a lot, have you talked to your doctor about your medications " that is if you are on any" that may be a good place to start. Best of luck for a wonderful future!!!
Hi there - thanks so much for your post. I try not to provide advice in this forum to teenagers or children because there can be other issues (like craniopharyngiomas!) that should be dealt with directly by a pediatrician or other specialist. Especially if there is a medical reason for your weight gain, this wouldn't be the best forum for you to look for a solution - I'm sorry!!