Lately I'll bet you noticed your body has been changing. You've started to grow breats and notice boys. Aside from the obvious physical changes you have been growing through, there is more than becoming a woman than growing extra body parts and smells. You will begin to notice a few things that are going to disappear.
The first thing you will lose is self esteem. You'll notice the girls with the bigger breasts who "put out" will suddenly have all the boys attention. This is normal. Boys experience this with their penis also. The best way to handle this is either consider becoming gay or "put out" alot more often than the pretty girls. Nothing drives boys crazier than a sure thing.
After that has disappeared you will begin to notice than you no longer have fun playing with boys and start wanting them to buy you things. Also a very important change you will experience becoming a woman. Having a good time will be replaced with insecurity and greed.
Next you will begin to lose the ability to make sense of things. If little timmy wants to play with his friends and you can't play because you are sick, does that mean he can't go out and play? Makes sense to let him go play with his friends now but just wait and it will all fade away.
Also you will become allergic to male happiness. As a girl you had fun when your guy friends were having fun also. As a woman you will feel the need to complain and bitch. Its because men excrete a certain aura when they are enjoying themselves that really pisses women off. You will be unable to control your mood as a woman.
And finally relationships will become much more serious. Instead of kissing and holding hands you will occasionally have intercourse, but only on your terms. Giggling and talking on the phone will become yelling at each other in the supermarket because he didn't give a damn if you two couldn't afford 2-ply.
As a woman you will experience many more changes that people can't really seem to care about but you. So enjoy the time before you start changing because it will be the last time you enjoy anything without someone getting yelled at.