Just a question on baby weights...

Ok so my first born was 7 pounds 10 ounces and my second born was 7 pounds 15 ounces and my Husband was telling a lady he knows that we think this baby (due April 29th) will be smaller then the first 2 because I barley am showing and I've been eating healthier this time around and have only gained 1 pound and my Dr said she might be smaller because I'm doing so great on eating and weight gain and this lady argued that no matter what your babies always get bigger so I'll probably have an 8 pounder this time, which is totally fine a healthy baby is all I want but is there any truth to that? Because I kinda wanted to call horse shit but she is one of those people who know matter what has to be right... told me my Dr didn't know what she was taking about and to switch my Dr... I love my Dr so that's not happening. But who here that has had other babies thinks this is true or false