2Weeks late, 3 negative tests.

My boyfriend and I always have protective sex. We had sex 4times only and he came 2 out of 4times. MY period is sometimes irregular. I was on my period the first timehe ejaculated (we used a condom ) however the condom slid halfway off. NOT completely. This was a month ago (march14) . It is now April and I was period becos my period didn't come.. I felt nauseated bloated and lost of appetite so I went to the clinic to get myself tested. The urine test at the clinic was negative, the doctor suggest to wait. After knowing that it was a negative the symptoms went away completely. I was paranoid again and the symptoms came back, so I took another test. This time, at home. At it was negative again. (1Week late). It is now 2weeks late so I decided to take another, this time it was morning urine. Its still a negative. I have no breast soreness, no cramps. I only feel nauseated when i think that I'M pregnant (paranoid ). Could I be pregnant with no symptoms? What should I do??? Help please!