Did you have a massive weight loss? If so, the "loose skin" complaint might be a valid one. If not, there may be other components to your perceived "loose skin", such as excess fat. The only way that you would even be considered for surgery is if you had a massive weight loss and now were left with skin that was stretched beyond its elasticity and you are finished with your growth phase. I suggest a visit to your pediatrician for a discussion as to whether your appearance is normal for a teenager your age or for a referral to someone that can address whatever your needs are, e.g. nutritionist, plastic surgeon, dietician. Good luck!