Jealousy issues?

Lately I've been feeling like a pile of ****. I'm 16 and have a all kinds of stretch marks everywheer because I was heavier b4 (lost 30lbs). But I know the stretch marks r there 4 life and i can't do anything about it. I can't cope though, expecially when I see girls my age enjoying their youth in belly tops and shorts with boys all over them. How can I get over this and move on with my life?