8 days late! Negative results

I am now 8 days late for my period. A week before I was supposed to get my period I went to the gyn, she I took a test and she came back in the room saying that it was negative. when I left she called me and said there was a faint line, so I came back the next day for a blood test which was negative. I took a test 2 days ago and that was negative as well. Now I'm 8 days late...I do not have symptoms. I keep getting the period cramps every now and then but no period