Hello, Irregular periods is caused by hormonal imbalance (like prolactin, oestrogen, progesterone,) hypothyroidism, reproductive tract infections, PCOS, anemia,fibroids, stress(not having good night sleep), certain medications like antipsycotic antidepressants, etc, you need to be examined first to find the cause, don't worry all can be managed with medicines or life style changes please consult a gynecologist.