Advice needed please

[sabtom]

So been ttc for a year now I'm more or less regular 24-27 days. My LP is about 11/12 days.

This month has been a little different, usually my BBT decreases just before AF turns up but as you can see from my chart it hasn't yet. According to my app I'm 15dpo and on CD 28. My opk's didn't get a peak but my BBT has confirmed I did ovulate, but when? Is the app correct? I've been taking a test every morning for the past 3 days BFNs. The first test was even a frer. What's happening? When did I ovulate, if at all? 🤔
The red "stars" in the pics are when we DTD.

Sorry just wanted to add, I don't normally get pms symptoms before AF other than feeling a bit crampy, but this month, nothing. No symptoms at all. And last night (tmi) after wiping there was the tiniest pink spotting and the same again this morning but more brown colour.

Anyone?