Last month, i started my period one week early. this month, i'm one week late. is that normal? am i pregnant?

Irregular menses: It sounds like your menstrual cycle is irregular, so your ovulation date is irregular also. If you've been sexually active and have now missed your period by a week, it's time for a home pregnancy test. They're easy to get at the drug store. Best wishes.

Cycle varies in teen: If you have been sexually active without protection then there is a chance that you are pregnant. However, it is not unusual for teens to have irregular periods that vary from month to month. Your cycle usually becomes more regular after a few years.