Hello, Me And My Boyfriend Were Dryhumping, He Had On

Hello, me and my boyfriend were dryhumping, he had on boxers and shorts, I had on underwear and shorts, this happened May 27, 2016, I had already gotten my period on the 5th, then on June 8, 2016 I got my period, after on July 4, 2016 I was wearing legging shorts and underwear, he was wearing only a condom, 5 days later on the 9th I got my period.After the 4th we have not done anything sexual. Now it is August 9th and I believe I have gotten my period only that it is light red and not dark as my periods normally are. It is brown and at times a very small clump comes out. Is this implantation bleeding. I have taken 5 Pt in total since the first incident (first response) they have all came out negative. But do to the different bleeding I am very concerned that I am pregnant. Please help me.