Could I still be pregnant?

HI, I'm 22, an about two weeks ago, I had unprotected sex. For the last week to week and a half I have felt sick and tired, my boobs are sore and swollen, I have been trowing up anything that i eat for the last four days. I thought it was just a flu, but i was suppose to get my period yyesterday and i have still not got it. So tonight i took a test, and their was only one line with a slight almost non eexistentsecond line. I ddon'tknow what to think, Any advise?