How can I gain more confidence?

I'm a 15 year old teenager stuck in the 'beauty-is-everything-age' and it's really grinding me down. I'm often complimented for having a fun, unique personality but I don't feel like that's enough. I'm not exactly ugly, but I'm no Megan Fox either! I feel like my friends are much more appealing and basically my confidence has hit rock bottom.
Also, I REALLY like this boy, and I think he likes me, but a part of me thinks I'm not good enough for him or something. I upped my exercise and lost weight and I'm at a fitness high, yet I still don't feel desirable as I am not the slimmest in my group of friends. It's really getting me down.
Does anyone have any tips on how to make myself more confident and feel comfortable in my own skin? Thanks!