Gosh, I don't know what to tell you here. Trixie didn't start to really look fat, at least as you are explaining it until about 1 or 1 1/2 wks before she delivered so I really don't have anything to compare it to. Maybe it could be because she was small to begin with?
I honestly don't know. Hopefullly some of the other vetran breeders will be on soon and they can help you.