Kmart!!! I have a Mickey shirt that says "Hey Baby!" They also have aTink shirt that says "High Maintenance" and a Pooh shirt that says "Hands off the Belly". Last time I was pregnant I got a shirt with Tink on it that says "Magic Inside". That is my favorite shirt. This is the only place I have found maternity shirts with Disney characters on them. Good luck and Congrats!!!
My wife is in the same boat of looking for maternity wear while at WDW, as she will be about that far along. She's trying to find a costume to wear for MNSSHP and is not having much luck. Has anyone seen any Disney type maternity costumes? Web returns aren't very promising....