no you do not, up to 120 pounds is a healthy weight for someone 4'11", I should know, I am 4'11'' and I've had this discussion with my doctor before. Your hips are probably just getting wider because of puberty, trust me, you are going to like your butt in a few years. Be proud of your curves, and trust me, 99 pounds is not too heavy. when you are 200 pounds, then you should see a doctors about going on a diet.