Confused and Confuddled...Am I or Not?

So here is the deal...Around the 3rd of June I had a very short and irregular "period" that lasted only 3 days and I had just ended my regular period 9 days before. Less than a week later I noticed that my breasts were quite sore and that I was getting sick to my stomach around the same time each evening, regardless of what I was eating. For a week I was consistently throwing up anything that I tried to eat, and then it slowly became a little easier to keep things down. My emotions have been completely out of whack, but On the 27th I started spotting and then 2 days after that "AF" showed up only it was incredibly heavy flow and almost like a water consistancy! 2 days of that and it returned to spotting. A girlfriend informed me that she got her period several times during the early stages of her first pregnancy and took 4 HPT that all came back negative. I've taken 3 pregnancy tests and they have come back negative and yet the doctor doesn't know what would be causing me to have these symptoms but he didn't do a blood pregnancy test. I would like to know what is going on with my body, and whether or not I should be going back to the dr and asking him to do a blood test to check for pregnancy...Any ideas or suggestions would be greatly appreciated!