I think most people get 'bump size' remarks, be it 'its small', 'it's big'... 'sure it's not twins'.
I think most people aren't intentionally upsetting us. Perhaps they are just trying to make conversation/small talk and don't actually realise how upsetting their comments can be.
When I was pregnant with DS my bump was huge. I got so many silly comments that I wanted to use the 'I'm not pregnant' line, just to see people back pedal.
Surprisingly being pregnant was the first time that I didn't care about my size or weight.
OP - try not to take the comments to heart. Enjoy the rest of your pregnancy. And if the comments gets really annoying try coming up with a one-liner