Implantation(?) cramping at 8dpo but still BFN

As the title suggests, I had some pretty strong cramping all day on 8dpo, and then some fluttery/twingy/pulling feelings off and on since then, but not full on cramping like it was on 8dpo. I’m now 12dpo but still testing BFN. O was confirmed with temping and CM. Shouldn’t I have a BFP by now if the cramps I felt on 8dpo were actually implantation???