Hello ma am and welcome. There can be various causes for irregularity of your menstrual cycle, let me list a few here so you can discuss them with your doctor as I cannot really pin-point the cause without a thorough discussion (two-way) with you. They are: +Stress +Medications +Infections +Systemic conditions +Abnormalities with the uterus (e.g. polyps, fibroids, etc.) +Abnormalities with the inner lining of the uterus (e.g. endometriosis) +Abnormalities of surrounding structures (e.g. polycystic ovaries) and a few others. Please speak to your doctor for an elaborate evaluation and appropriate management. Hope this helps. Best wishes.