It really varies. You could have more fluid this time, or the shape of your belly could look more 'poppie', like a basket ball under your top LOL. Sometimes I think too that people have an expectation in their mind of how a pg woman 'should' look at a particular gestation kwim? With my 1st and 2nd pg's I had the exact same fundal height with both of them at the same stages of pg, but with #1 I looked a heck of a lot bigger because i was a different shape. I was a lot more rounded with #2 but with #1 it was pointier.