This may sound a bit harsh but have you been told by a medical professional that you need to lose weight?
Your family may see a perfectly healthy teen at a healthy weight and are not trying to sabotage your "success".
The Hollywood norm IS NOT a real world norm to try to emulate.
You need to get an honest evaluation of your weight before trying to diet. Also, severe dieting at a time of growth and maturing can have nutritional repercussions.
"To give anything less than your best is to sacrifice the Gift."