I'm 13 (turning 14 in a couple weeks) I have had my period for a little less then a year. But a couple months ago, I didn't get my period for 3 months. Then I got it for 23 days. And it stopped, but after a week and a half it started again and it's been 13 days! I get stressed easily, excersize a lot! (Running 7 miles, core, lifting, dance), I didn't get my period for 3 months at the end of school and my period started the day that summer started.