Am I ok with my size for now?

I'm going to be 15 in February. I'm 5' 5" and a half, and 117 lbs. Im pretty skinny, and I can only bench 3 reps of 100. I'm embarrased about my arm size alot... people tell me i'm good looking, girls and elderly women relatives, of course :-) (not trying to sound concieted) but, my physical features down my self confidence.I don't lift regularly. I've only lifted 4 times in my life.. I'm embarrased to go lifting at my school because all the jocks and good, strong, fit athletes are in there, and i'm afraid of getting made fun of, and I feel like a misfit, especially because my school is ALL about sports, and if your not good at sports (mostly football, basketball, and wrestling) like me, you're a misfit... I tried football, but I quit because I was bad at it, and I didn't like it, and I tore my quad like on the 5th day of practice. I need advice please? Am I ok to be like this, or do I need to step up to the plate? Thanks.