Don't worry Danni, both my kids I had a small belly and then towards the end it got big. Remember that bub is aboug 2kg at...whenever, maybe at the start of the 3rd trimester, and so they about double their weight from then til their birth. Plenty of time to pop.

Another thing is, if you're taller, then there's more room upways and not yet the need to stretch outwards. Or bub could just be nestled a bit further back. Or you've got good abdominal muscles. Plenty of reasons you might not have a huge belly yet.