Missed period on Metformin

Hi everyone!! I have a question. I’ve always had irregular periods. They would occur every 21-28 days and bleeding in between from time to time. Periods would last 5-20 days. I’ve gone with other women’s health providers that told me this was normal for me. I was on birth control for about 8 months. I then stopped due to SE’s.

I moved to a different state after graduating college and to move in with my husband in April of 2018. My cycles became more regular (26 day cycles).

After 8 months of ttc and my pap and wwe due. I went in to see an OBGYN. I explained more about my cycles (her asking me to distract me from my pap) she began asking more and more questions. She then told me I had physical signs of insulin resistance and had suspicions of PCOS, she mention she would hold off on testing since I haven’t skipped periods. I was prescribed Metformin ER 500 mg once a day by my her, stating it would help w/ insulin resistance, and if I did have PCOS it would help as well. She stated from explaining my past cycles, it seemed as though I wasn’t ovulating before, and that it seems that I was now from my weight loss ( lost 75 lbs and I would get breast tenderness and CM during time of expected OV which before didn’t happen and but also from opk I wasn’t ovulating so I’m not sure) she mention Metformin would help me ovulate if I wasn’t and asked to schedule on May if I haven’t become pregnant to run testing on myself and possibly my husband.

Once I got home I started on Metformin, my period was due soon and was same as usual.

After that my cycles changed to 23 days with 3-5 day light bleeding.

My LMP was on Jan 17, 2019. Today I am on day 25 and no signs of a period (cramping or spotting) or signs of pregnancy since my only sign would be missed period. I took a hpt and it was negative.

Has anyone who has been on Metformin for PCOS, insulin resistance or DM ever missed a period while on it?

Thanks in advance for any help!!