Enormous baby bump: Is it normal to look more pregnant than I really am
I don't think there's any specific size of bump you should have at any given time. I'm a bigger girl so I couldn't really see a bump until I was a good 6-7 months along, but it's different for everyone. Baby could just be sitting really high up or low down and that could make the bump look bigger.
I remember laying in bed stretching out on my back for a moment and seeing Charlies head, big as a bowling ball sticking straight up from my chest.. haha.. scared me :)
I felt huge with my son but I felt like I barely showed with my daughter until the end.