Triphasic and spotting.. But BFN

[Bumpler]

Hi ladies I'm new here and hoping you can help. I have a Triphasic BBT and a light 3 day bleeding around the time implantation would be likely with an implantation dip. I'm due AF today but still BFN. With my previous I tested positive 5 days before AF. I'm so confused, I'm thinking the three day spotting may have been AF but I never have irregular cycles and wouldn't explain my BBT chart??