Cutoffs just don't help people get pg. It is not at all unusual for people to take that long to get pg using a cutoff.
If you think you aren't Oing until the later end of the window, by all means DTD 12 or 24 hours after that first positive.
Just out of curiosity, did you have more than one attempt (so attempt on O-2 and then again on O day) or just one attempt on O day?? I would stick with one attempt in fertile window, that seems to be getting best results.
I understand it feels like you aren't swaying, but a LOT of "swaying" is just background noise that does little to nothing except preventing pg. You have to do what you can live with above all else, but there have been tons of people who got opposites from uberstrict sways and then others who drop everythign and get their DG.
