please don't judge me 😅

Ok so please don't judge me. I feel like I should know this by now but I'm still confused. I just recently got married and just recently started having sex. We don't want kids any time soon (but if it happens, we won't be upset) and I know other women who use "natural birth control". One of my friends uses the pull out method and her twin sister has protected sex only when she's ovulating. I use the pill. But my question is, how do I know when I'm ovulating?? And what's the difference between that and being fertile?? I just checked my cm (I'm guessing that's what it is?!) and it's completely clear. When are my chances of getting preggo high? Should I not have sex when my chances are high even tho I'm on the pill?? Halp! 😫