Women cycle differently and each woman will experience variations in her menstrual cycle throughout her life, especially at times of puberty, after childbirth, and at menopause. A long cycle may also be a miscarriage of a short pregnancy.
If you have been on your period for two weeks, this could be because you are experiencing hormone irregularities. It may also be linked to a problem in your uterus, such as fibroids. See a doctor if this is not normal for you.