PCOS help

I had some labs done and was told I have PCOS I am TTC but the doctor told me we would have to go through a lot of tests so I decided to wait and try to lose some weight. She prescribed me the birth control pill and also Metformin, I am confused because I thought Metformin was used to conceive. So I'm wondering if I accidentally miss a pill could I possibly conceive? And if that's the case why not just take the Metformin?