Most common cause of irregular cycles is polycystic ovarian dis which is due to hormonal imbalance. Most common cause of PCOS is stress , obesity, unhealthy lifestyle. thyroid disorders also cause irregular cycles. Wht is ur weight ? Due u hav acne or facial hair pblm? To diagnose PCOS get an ultrasound done. U can start birth hormonal pills to regulate ur cycles. Pcos sometimes causes infertility.