Ladies who experience EWCM

Heven
So this month I've increased my water intake tremendously. I mean going from never drinking water to drinking 8 cups a day to improve my CM. yesterday after I used the restroom I wiped and got a lot of EWCM for the first time in a long time (I never check my cervix, I just notice some CM when I wipe) I hadn't taken a opk in a few days but my husband just got back from deployment and we BD the day before and day of. Today I took an opk and it was negative. Possible I still ovulated yesterday? Or would I still be getting positive opk of I did? How long do y experience the EWCM? I also had some backache which I know can be a symptom of ovulation!