Pregnant or hypothyroidism ??

I have three children and after the birth of my third I had my tubes tied. That was in 2001. In 2002 I had to have uterine hydrothermablation done. I had my thyroid removed in 2004. My tsh levels have been around .197 every since then. I have weighed between 122 and 128 for the past 7 years. I have recently started gaining weight rapidly. I have gone from 128 to 147 lbs in 3 weeks. I had my tsh checked and it is now 3.0127. I look like I am 5-6 months pregnant. My butt and stomach are getting big. My breasts are falling out of my bra. I have always been very small. My breasts were barely a B cup 3 weeks ago. I have never had a butt. Recently at times I think I feel something moving in my stomach. I took a home pregnancy test and it was NEG. Could I still be pregnant after all this? COuld that be the reason I am rapidly gaining weight? Or is it my hypothyroidism??? Please help me! My family and friends all think that I am pregnant! Even my husband thinks that i am. Please help!!!