7 days late, implantation bleeding!?!? What is this?!?

Mary898
My AF was due 8/9 and I am 7 days late. I was supposed to ovulate on 26th of July however I am suspecting that I ovulated on 1st or 3rd of August. I didn't test my ovulation but this was the last time that I had sex. 
For last 7 days I didn't have any implantation bleeding at all. Today I just had a very light pink spots and then brown discharge for the one time after toilet. 
I have cramps and fatigue. I used to feel bloated and my appetite is gone! I am just tired... 
My period never gets late all my life but now I am getting BFN's after 6-7 days with home pregnancy tests
What is this exactly? Did I ovulate late and implantation is just done today and does my HCG hormone will build up after today? Am I gonna get my period??? Or I am just pregnant?! Any idea!?