Fallback Rise or Late O

Meg

I have pretty consistently been ovulating around cycle day 17 or 18 with EWCM to match. I had a rise of almost .3 on Friday morning so assumed I had O’d on Thursday but then, this morning’s temp, dipped back down again. I had some creamy CM this morning but nothing fertile. Not sure what to think as I didn’t take OPK’s this month because I was drinking so much water, my pee was always too diluted. Thoughts?