Am i fat i want to loose weight?

im about to turn 12 may 26 and i weight like 140 something i used to weigh 153 or sum like dat and than i lost like 20 lbs or sum like that and than i gained some pounds and so now i weigh 140 sum and im going to do athletics and i want to loose some weight so i can have a better chance at making the track basket ball and volleyball team and even if people say im fine i really want to loose some weight so can you tell me how and if there is any online videios that can help me tell me