Boy problems ruinin my friendship?

My best friend it thinner then me by 4-5 pounds because im 7 and a half stone an 13 years old. everytime i like a boy i try to impress them for ages but then wen i find out who they like they seem 2 always like my best friend !! no amtter how i act or wat i do they neva notice me? im just the pretty ones friend .. help ? we have fell out over the fact but then i amke up with her cuz its not her fault but i feel so jealuos an it makes it worse cuz i like some1 now an hes likes her as well !! im movin 2 america 4 a year then comin bk 2 breitain an i dunt no wat foot to leave on with my friend ?? help plz!!