confused

ok my period was two weeks late. I took a hpt on Saturday and it came back negative. two days before I tested I notice a little pink when o wiped, its now looks like a normal period but it is very very light. I normally bleed through a tampon and a pad in about two hours. I actually have to get up during the night to change. last night I wore a normal pad and didn't bleed through at all. could it be implantation bleeding or a very different period. please help