ANDY'S ANSWER: No, your period won't be coming for a while, but tenderness in your breasts means that you have begun puberty. You must have noticed that your nipples have begun to grow and bump out a bit. This is called "breast budding" and is the first sign of puberty in a girl. You can expect your period around 2 years after the first signs of breast development, so make a note in your diary to be prepared for your period sometime around summer in 2015.