Ballerina Deficit

Hi so I'm a newbie here and I've been feeling hated by my body lately. I've gained twenty pounds in six months because of the pill. I dance ballet and every week whenever I looked in the mirror I only saw my butt getting bigger, my stomach flabbier and bigger. I did swim team in the fall and lost weight, but I have NEVER so comfortable with my body to wear a sports bra and shorts to my jazz class. Everyone else does but I dont. I hate this feeling of looking and feeling gross. I realized recently that I dont suggest going to the beach with friends because of my stretch marks on my outer and inner thighs and my flabby stomach. I have older siblings, one of which is an a-hole. I wanted to start Insanity but he was like " no you just want an easy solution to your fat issue" and then he tried to tough my stomach. I screamed at him and ran to my room. Maybe he was right... I'm going to a new school this year and I know about 20% of the population from elementary school.. all of which did not like me for being the quiet weird one. I want to go back in time to myself six months ago and tell myself I was beautiful. I now hate how gross I look, how i'm always in the sun with my lifeguard suit on getting dark everywhere but my stomach. I have to go get my stomach tan to match my body but I dont want to face the beach or the world with my fairly new self image.