Please help me! See the info box for the question.?

Both my parents and my older sister have had gastric byp. Obesity and diabetes run in my family, so they had that to reduce their weight. They all lost drastic amounts of weight, leaving me, a fourteen year old, and my by at least ten years older brothers large, and unable to do anything about it. I am 5'6" or thereabout, and I weigh 172 pounds. I don't look fat, but my joints are already starting to give out because of my weight, which also runs in the family. I don't know what to do. Please help me? I weigh more than my dad, and I feel awful. Help.