Oh man I've copped so many of those comments lately.
'Your bumps way bigger this time, this kids gonna be huge!'
I had the same thing! (although I secretly thought I was bigger too)
Funny thing DD1 was 2987g and DD2 was 2900g, and only 3 days between gestation.

Oh Kel, I feel for you, it is the only time that I did not like being pregnant, when people gave unwanted comments/advice.
Don't let them get to you just enjoy your lovely 'big' bump .