How do I stop comparing myself to other girls?

[myira_shine]

I think - or rather, I know - that I am very pretty. I look at myself in the mirror and even though of course I have bad days where when my hair isn't done I feel gross, most of the time I think I would rate myself an 8 or 9 out of 10. There are definitely things I like about myself and things I don't like (I love my teeth but I'm 5'8" at 132 and I want to lose 8lbs). But the problem is: I always feel like I have good self-confidence until I go on Facebook and I see pictures of girls who are just gorgeous. And that's when I feel ugly, too tall, clumsy, and I become aware of my broad shoulders, the fact that my hair isn't as long as I want, the fact that my leg doesn't look as thin as hers does when she bends it, etc. It's awful!

For example: I have a good friend who's cousin is in my opinion, just gorgeous. She is very photogenic (which I am not) and it's embarrassing to admit, but even though I hate looking at her Facebook pictures because it makes me feel bad, I do anyway and it's like self-torture. This happens with other girls too who I know in person and who just seem to always look beautiful. How do I maintain a level of self-confidence when I'm not by myself? How do I stop comparing myself to other girls? I'm 21 years old, so the old "high school" excuse can't be used anymore.