Sometimes periods are a little late with timing. Just give it time and you'll have it. Wear pads for the next few days just in case. Periods are suprising. If you had it for two weeks last month, then it might skip this month. For further reference you should talk to your mom about it. Hope this was helpful sweetie!:)
It could be stress, maybe you counted the days wrong. A woman's body is soooo complex and annoying. LOL. If you didn't count wrong, its just being a pain in the butt and decided to be late this month. If it doesn't come in the next week or so, go to the gyn. Maybe you should go on birth control so you can regulate it. I did and it works like a charm. No more surprises. You know exactly what day it's going to come. Good luck Love
Other than pregnancy, late period can be caused by; stress or anxiety in your life, you may be having hormonal imbalance or you might have engaged in vigorous exercise and athletic training. If you happen to miss your periods for three or more cycles, it would be better you seek professional medical advice. For more information, visit http://womenshealth.about.com/cs/menstruation/a/lateperiod.htm.