Cm question

So I ovulated on 3/31.. I was just wondering if you have to have cm to know you're ovulating or to know that you conceived after ovulation? We bd every day of my fertile window so maybe thats why I couldn't tell how my cm was? opinions? I took an opk twice everyday starting after my period cause I didn't want to miss it so I know for sure according to my opk that I ovulated on 3/31