Metformin for PCOS

Hey, recently I was diagnosed with PCOS and for the last month I’ve been on Metformin. I haven’t changed my diet besides exercising more and not so much fast food. I’m down 11 pounds.

My period was supposed to come on the 18th, never came. I tested and got a negative, so I waited until this morning day 4 to test again, still a negative.

My question is, anyone put on Metformin for PCOS and stop having your periods? My periods were regular and always on time before this month. Should I get my hopes up? Or is it just the Metformin messing with my cycle?