Have PCOS since in my teenage,I m 30 years old now,and never been pregnant before in my life, having unprotected sex for 6years to get pregnant and also been seeing doctors ,I was placed on metformin 500mg three times a day to regularized my period because my period was never regular since I started having period in my teenage,the metformin did worked for me by regulating my period for almost a year now but all of the sudden while still on the metformin my period have been missing since three(3) months now,did pregnancy test 5times negative what is going on and what can I do to get my period back.