I just went to visit a doctor and they did some urine test on me which came out negative

Hi, I am just 17 and I just had sex with my boyfriend on the 28th July 2013, which is just 6 days ago. We had unprotected sex but he was sure that he didn't cummed on me while we are having sex. Recently right after the sex, I felt bloated on my upper abdomen and I have mild cramps occasionally on the lower abdomen. I also experienced loads of vagina discharge. My last period was on the 29 June and I am having irregular periods due to my school stress. I just went to visit a doctor and they did some urine test on me which came out negative. However, after i took the medicine they gave me, the bloated-ness feeling didn't go away. Is that an early symptoms for pregnancy or my period is coming soon? Am i pregnant? Please, I am not prepared for motherhood and I don't think both my boyfriend and i could afford this child! Please help!! Much appreciated!!