Implantation bleeding?

Okay guys so my period was supposed to start the 11th, today makes it 8 days late. All 3 tests were negative. I went to the bathroom about a half hour ago & when I wiped there was a very light pink like discharge on the toilet paper but I don't have any cramping. It hasn't gotten any heavier yet. I've seen that many women who have had implantation bleeding it has happened before their expected period but I've also seen women who have had theirs after their missed period. I don't really know what to think. Can anyone help me out?