Baby's size

I am 30 weeks and 3 days. Today I had an ultrasound done and I was told that baby is about 3.1lbs. They told me that she is pretty small, but Glow estimates weight for today at 2.9lbs? I don't want to be worried over nothing 😩 My first daughter weighed 6lbs 14oz when she was born so maybe my SO and I just make small babies? We're not very big people lol What is the estimated size of everyone's babies?