Does bump size matter during pregnancy?

Okay so this is my first pregnancy and I’m carrying quite small. I still have a visible bump but everyone is always commenting how little I am. My mother in law said “I hope that baby is growing like he should, I’ve been worried since you’re so small” & that scared me. When I went for my 3D ultrasound he was measuring 2 weeks ahead and 3.4lbs so he’s right on track for where he needs to be. But I just feel so bad and worried because everyone keeps saying stuff 😭.