I do the exact same thing! (I'm 6 months pregnant)... I feel horrible afterwards, my fiance is really great and he waits on me constantly, he's always doing something for me and then I fly off on him. At first he'd get insulted, but then he started to realize that it wasn't really me. Now, he just says, "Chan, are you just saying this because you're pregnant?" At first it made me so mad! But now, when I take time to think about it, the answer is usually yes and I'm able to back off.
BTW, welcome to JM!
Hey, I just realized that we're due at about the same time, you're just 2 days before me (Aug. 28th)... We're 2/3s of the way there! Wohoo!