17 dpo

So I should have gotten AF a couple of days ago and I’m a little crampy but no spotting or other symptoms really besides my boobs feel a little fuller and a little sore but not terrible. I looked back through the last 6 or 7 months and I got my period, every month, 15 days after my predicted ovulation day exactly with the exception of one month which was 14 days after. I did a pregnancy test yesterday and it was a BFN. Wondering if I took it too early or if anyone had taken one 15 dpo , got a negative and then got a BFP later!?!?