CM experts please

I have a few questions. I found a chart online that kind of explains what to expect during the whole month, but I'm confused. My last few cycles I get to a point-about a day or so after my calendar says my ovulation week was, and during sex I'll have a lot of white odorless, kind of thick discharge. I've never had this before. Can anyone explain why this has started for me out of no where, and what this kind of discharge means? It's happened the last 3 cycles. No infection because it goes away after 2 or 3 days and I'm not itchy or uncomfortable and it never smells. Any advice would be helpful. Thanks in advance!