Large fundal height and abdominal muscles

I wanted to ask this question in a group who has already had their babies. I am 22 1/2 weeks with my second. I had my first 16 months ago and he was a textbook perfect pregnancy. 6 months ago I had surgery to remove my spleen which meant cutting about 4 inches into my abdomen below my belly button. Since the very beginning of my pregnancy I have been measuring 2-3cm further. At one point my doctor thought we might be having twins because we were easily able to hear a heart beat at 8 weeks, started feeling movement super early through an anterior placenta, and my uterus was always so so high. Then at 15 weeks I was diagnosed with low amniotic fluid. We have been able to bring it up to a safe, but low level. Which usually means measuring smaller not bigger! Today at 22+4 I was measuring 25cm. I had my doc triple check! BUT, our dates are right and at our anatomy scan he was measuring EXACTLY for his due date minus a big belly (my oldest always had a big belly too). My oldest was born 8lb4oz at 40+1. I’m wondering if anyone has experience with this and what was their outcome (as in did they have a big baby or go early?) or have any idea why it’s always measuring much further despite having very low fluid and the baby not being further. Could it be from abdominal muscles easily stretching or something?