metformin Rx question

So I messaged my doctor today and they never got back to me. Anyone take metformin before? So here's my question for people who have. My cycles were normally about 23 to 26 days apart with usually cramping and sore boobs before my period also diarrhea (tmi I know) well it's now day  25 no symptoms nothing so does metformin make my cycles longer? Why don't I have period symptoms? And yes I took a pregnancy test last Thursday it was negative 👎 so anyone know? Thanks ladies!