Fundal height

I had my 28wk appt and was measuring 26wks. I always measured behind with my daughter, but did have her early (no reason why, water just broke) but she was “big” for 34wks at 5lbs 3oz. She was seriously one of the bigger babies in the NICU. So I’m not really worried......but worried about having another preemie if it’s a correlation. Anyone else measuring behind? I feel huge since this is my second (showing sooner), but I guess I’m not really. I have a growth scan scheduled for 36 wks (hopefully will make it to that 🤞🏻). My OB did not seem concerned yet that I’m measuring smaller , but I can’t help but worry some. I just don’t want another preemie. I’m petite (100lbs pre-pregnancy 5’3”) and my husband isn’t a big guy (he’s 5’8” 150lbs) so I think genetic wise... it would be super strange if I had a huge baby. Kinda rambling now, just curious if anyone else measured behind and if their OB is concerned.