That happened to me spiceoflife! Finally caved and test, BFN

It's hard to say though, because you said you don't know when you O'd. When you get AF, does she come in a bang? I never get pre-spotting or anything, just flood gates open! So I don't have those 'oooh is that implantation bleeding?' thoughts.

But, if it's late - POAS, for sure. At least you will know. FX.