Having a strange AF, anyone have this problem?

Okay, so my whole life I have been very regular. Every 28 days on the dot. The only time I was ever late in my life was when I got BFP with my daughter. My LMP was 3/15 and I was supposed to get AF on 4/12. I ended up being 4 days late. I got 2 BFN's from a HPT. I then went to the doctor to get a blood test (that is a whole other story!) and did not get it done. But while I was giving the urine test I started to bleed a little bit. I have been having AF but it is not the same as it usually is? It is very light and I have no cramps. Even though I have 3 BFN's by urine tests, I feel like something isn't quite right? I have to go back for the blood test, but has anyone else been through this? I am so confused.