Pcos metformin 3months late af?

Ashley • 23yrs old Ttc 1yr for bby#1 have pcos husband has low sperm count
So just a question ive been on metformin for 3 months now i have always had pretty regular af I always started either before or when i am suppose to but now i am three days late an negative test i took it the day before my due af just curios at the time but now im kinda worried. Can the metformin make my af miss or anything please help need answers