So, I got on my period August 31st and my last day was September 4th, and I was supposed to get on it 4 days ago... And I had sex like 2 weeks. But I took a pregnancy test last week and it was negative but I'm still worried about it because I haven't gotten my period and I've been having a lot of headache and cramping and I did a test to see if I'm about to get on my period and it said no. So, I don't know what to do. Can anybody help me?