Should I Bother Taking Birth Control If I Don't Ovulate and No Longer Want Kids?

I have PCOS with Insulin issues. I had to use Metformin to get pregnant with both my babies since I wasn't ovulating. My husband and I agreed we're done having kids. Do I really need to use some kind of contraception if I had to take medications in order to get pregnant in the first place? It seems kind of silly and there doesn't seem to be much research on it. My OB said "there's always a chance you could get pregnant", but they don't really acknowledge my PCOS outside of when I wanted to get pregnant.