Big changes inside. Your ovaries are maturing. Your brain has stimulated the release of hormones that you'll need later for menstrual and baby-making functions. Changes start on the outside. The nipples and surrounding area called the areola, are getting darker and growing a little bigger.
Pubic hairs appear.
You'll probably grow taller. Your hips, thighs and butt may begin to fill out. Don't worry about a little extra weight. You're supposed to put on a few pounds. A certain amount of increased body fat will help you develop properly.