Implantation bleeding??

I was expecting AF last april 1 but it never came but i got this very light brown bleeding/discharge since april 2.. is it implantation bleeding? Ive tested 6x and all are negative. I also did hcg bloodwork on april 2 and it was 0. Why is my period still not here? Could it be possible to still be pregnant and the hcg hasnt rised up yet? Anyone have any experience with this??