Pregnancy

My last period was Aug 4.2008. I have been experiencing breast development tenderness, vomiting (stopped), fatigue (very tierd)I took a blood test on Aug 29. it came back negative. I have been bloated for the past week even sitting down is uncomfortable, my jeans are a bit tight around my waiste line. I also forgot to mention that my fiance and I we've been having unprotected sex. September 3.2008 i was spotting with mild period cramps until Sept5.2008.On the 5th I did a pelvic ultrasound there was nothing(no cysts) Sept.09 I did another blood test and it also came back negative. I am still experiencing symptoms. I don't know what to do anymore is it possible I could be pregnant but the placenta has not been formed as yet in order to produce hcg?

Please help me I am going crazy!!!