Kate, I used to do the same thing in pictures (not smile 'cause of my gapteeth). But I finally decided fuck it, I'm gonna smile! I hope Ты get to be comfortable enough with your smile to Показать it off someday. :)
Ты have average looks, your not strikingly beautiful but then again most people aren't including myself. I think people (again myself included) tend to base their looks on Знаменитости and people who are for lack of a better word are еще attractive, so we feel down about our selves and think we are ugly by comparison. But that's like being mad at yourself for not having a million dollars like someone your own age who inherited it, its out of your control, the best Ты can do is be happy your looks aren't below average and just live the best life Ты can.
On a side note, I don't want to say Ты have to be happy with your looks if Ты don't want to but Ты do have to except them. Ты can mold them to be еще appealing (to yourself) because in the end if Ты don't think Ты look good, anybody else's Комментарии will be meaningless to you.