Ovulated CD 12?

I have normal 28 day cycles and I took an OPK on CD 12 just one in the afternoon- I figured I'd have plenty of time to keep testing but to my surprise it was very dark and nearly positive. I didn't take another that night. The next day it was significantly lighter but you could see a line pretty clearly and since then it's remained the same, for days. I'm now CD 16. It hasn't yet gone negative but I feel like I already ovulated, and at this point I'm starting to believe it, too.

I just don't understand why my OPKs haven't gone negative yet.

Also, we only BD'd on CD 10 & 11 because I thought we had time now I don't think so and I think we missed the boat 😞

Thoughts?