How do you know if your breasts are growing as a preteen?

I'm in the preteen stage and i'm worried i'm behind adjectives the other girls in my echelon. (5 - i'm 11) I want to know if my breasts are growing (coz i'm as flat as a board). I wanna know if i'm encountering one of these stages. PS. Maybe this would be a dutiful question for females singular, thanks!
Answers:

Has anyone ever cried within the middle of having sex?

every girl is different. they come within all ages and sizes.
logically you are flat as a board, you are only 11, i would be surprised if you weren't!
they will come, don't verbs. you can ask you mother/aunt/sister and compare, because these things are usually genetic.
postpone the worrying for another 4 years, please

Barbie, a role good model?

just continue, be patient they'll grow. sometimes you can grain 'growing pains' around that area and after you can tell they are. but don't verbs, you'll catch up!

Birth Control?

It is average for girls to start developing at different times, as early as 8 and as belated as 15. So don't worry--you are fine. Breast growth begins near puffiness around the nipple only, and those are call "breast buds". That is the first thing you should spy. Then within a year of that, breast tissue should start to form around the nipple within varying degrees, depending on your body type. There is a great book put out by American Girl call The Care and Keeping of You that you can either buy at any book store or win at the library. It is a general form book so it isn't something to be embarassed about buying or asking for from the librarian. But it does a nice commission of explaining things to girls your age. Good luck!