Implantation bleeding or period?

My period was supposed to start yesterday 06/28 and has not started. Yesterday I wiped down there and my toilet paper had a light pink color blood to it like nowhere near enough to soaking the paper. Today I wiped in the morning again and it was a light brownish pink discharge again. I usually have a heavy flow and it should have already started. On the 26th I took one HcG test and it was negative. What do you think?