M y periods are 8 days late, I haven't had sex, am not stressed, I eat same foods I always do, no weather changes etc what could be the problem?

Your name would suggest you are 13? When did you start getting your periods? Sometimes when you are young, periods can be a bit unpredictable. Do you have cramps or any of the other symptoms that you would normally get before your periods? I wouldn't worry too much honey, but if you haven't gotten your period by the start of next week, maybe you should make an appt with your Dr. just to be on the safe side, to make sure there aren't any underlying probs. :)