I have not had a period since May 7th of this year. I taken 4 pregnancy test and had a blood test done and they all came back negative bu I still feel pregnant and have symptoms. I've gained weight, had morning sickness back in June and July and by boobs are tender all the time. I'm constantly going to the bathroom. I don't know what to do.

There have been cases where woman don't know they are pregnant and show no signs of being pregnant (as in morning sickness, or showing much weight) Although if you have gone to a doctor and he comfirms that NO you are not pregnant then you may have to go to your doctor and figure out what's wrong/going on. (just out of curiosity, how old are you?)