Is This Implantation or AF?

I'm on CD33 and I'm 12dpo. Originally I thought I was 15dpo, but a few ladies taught me some more about bbt charting and suggest I move my ovulation day from CD18 to CD21. My temp dropped this morning, but it's still above my cover line on both apps. Is af coming tomorrow or is this implantation? I was cramping last night on both sides and my upper abdomen, but it only lasted for about 4 hours, then it stopped and it hasn't came back. I had BFN's yesterday and the day before. I also have A LOT of creamy cm.