Ovulating Late

Fran
Talk me off the ledge here....
My husband and I have been TTC for 3 months. After two months of BFN I bought an OPK, this cycle I got the positive surge on CD18, which is later then I thought it was happening which may have been the issue with the first two months. The business trips my husband has had this summer seemed to always land during part of my fertile window. Luckily this time he was flying in the day I got the surge. So we were able to BD that day and the two days after.
So here is my question. Today is CD28 which like clock work I usually get AF but so far I have not. Two days ago I got the usual back pain I generally get before AF, so I thought so for sure this was not our month, again. The back pain and slight cramps lasted most of the day but not bad enough to take any medicine for, which is uncommon, usually they are unbareable.
I still have not started AF today, no cramps, and no BFP. Do you think the late ovulation is causing me to wait a few more days to test?
-hopeful & confused.
🙏