what if your peroid is late but you havent had sex? I was a little more that a week late last month and this time I am late again its been a few weeks.
If you are young, periods can come sometimes at irregular times. It may take several years for them to even out. Diet, excersize, sleep, stress, can all effect the timing of your periods, especially in the first several years. If you have been "with" a guy in any way that could possibly cause pregnancy (I do not want to be too graphic here) than you should purchase a pregnancy test kit, or visit a planned parenthood clinic to get a pregnancy test so that you can know for sure. Otherwise, talk to parents, school nurse, trusted teacher, school counselor, etc.
It's nothing big. I'm still a virgin and my period sometimes comes late. This all depends if you have been with anyone at all. But it also depends on your health. Such as eating, sleeping exercising, you know things that keep the body running. But I don't think it's serious.