This might sound crazy, but there are women who have psychosomatic symptoms of pregnancy, even ones that seem impossible to "fake" or wish into existence. I’m not saying that’s what is happening with you, but it is possible. I’d go get checked at a clinic or doctor. With that much growth and negative pregancy tests, you could have something really wrong, especially if you haven’t been eating much more to cause weight gain. Are you growing all over or just in your midsection?