Calculating O-Day

Okay I feel pretty dumb...we’ve been TTC for about 5 months. I’ve been using OPKs. And now I think I’ve been calculating it wrong the whole time 😂🙄

How do y’all figure out how many DPO you are? I’ve just been going off of when I get my positive opk...but now that I’m thinking about it, would it actually be a day or 2 AFTER I get the positive, right?

This whole day I’ve been saying I’m 15DPO bc I got my positive opk on Nov 27th. I got a BFN this morning. I started feeling a little crampy...checked for CM and saw some brown/red CM and assumed I was getting AF. Put in my diva cup, checked it hours later assuming it would’ve been halfway full, but there was only like a drop of blood in there. Normally when I start, it’s like FULL-ON and I need my heating pad for the horrid cramps.

LOL sorry for the rant. But what if I’m only actually 12-13DPO? Is this even possible? I’m graspin at straws here ladies lol...could I be implanting right now 😩😩😩