Can someone please help me?

I was told yesterday that I have pcos. We are ttc. My doc said that we should hold off on trying for 3 months or until I adjust to the Metformin that she prescribed. Now this morning I got a bfp. I'm super excited and scared at the same time. When I called to ask if I should still start taking met even though I'm pregnant, they said yes. I'm confused. Why did she want us to not try while I started on met, but it's ok to start met while I'm peg? Help