Birth Control

I thought I understood how birth control works. Birth control helps stop ovulation, right? Can someone explain this to me. I was at my doctors appt. and I was explaining how I started to have no periods at all even on the last week of pills when I'm suppose to start. I've been on Gianvi for two years and always had a period when I'm suppose to. She said "don't listen to any other doctor, no period is great, means you're not ovulating." I've been on different types of birth control for a while, because I struggled with PCOS since highschool. Now that I'm married and I want to make sure there are no surprise babies 😅