ANDY'S ANSWER: 10 is on the early side to be starting your period, but it's still normal. Not every one is exactly the same. The average age to get a first period is 13, which means that some girls get it when they are 10, 11 or 12, and others don't have their first period until they are 14, 15 or 16. Because you've started your period earlier than others in your class, it stands to reason that your breasts are more fully developed than others your same age, since breast development is one of the first signs of puberty starting. The others will soon catch up!