37 days late ??!

I have not had any symptoms at all. I once had cramps in the morning but it went away and later on they came back but since then nothing at all! I received my period 2 days after sex and it lasted all week but this month I'm 37 days late and haven't had sex since then. I took a pregnancy test about 2 weeks ago and it was negative but I don't get why it still hasn't Came !!!