AF 3 1/2 days late and getting BFN.....question

Alyssa

My AF was due 3/31......she still hasn't shown up. I took a FRER and a FR digi and both were BFN. I took a dollar tree test yesterday and one today....I think I might have gotten a VF line. I will include pix of those....but my question is....has anyone been this late and still got BFN only to get a positive a couple days later?? This upcoming Thursday I will be 1 week late.

My periods are always regular.