Help!

I am almost a full week late. However I have already taken a pregnancy test that came back negative. Also it is next to impossible for me to be pregnant because I use the pull out method. I know that you could technically still get pregnant off of the precum but that is highly unlikely. Especially if I wasn't ovulating. So with that being said, I don't think I'm pregnant. However, I still have no idea why I wouldn't have gotten my period yet. Does anyone have something's I could look into or what might be potentially wrong?