OVULATION DATE CHANGED ON ME?! Help!

De

Here is my month of July showing my period. During July I used OPKs and got 2 positives on the 25th and 26th. I BD every day that’s got a red heart (almost two weeks straight) and even went and BD 2 days after my ovulation date (which was the 26).

I got my period this month and saw that my month of July ovulation date changed to the 31st! But how?! I didn’t even bother to test after the 28th since I was getting low OPK results.

Should I have kept on testing and BD? Is this why I possibly didn’t conceive? How confusing.

PLEASE HELP!