Measuring large at 26 weeks

Kelly
So 26 week appointment I am measuring 30 weeks. My dates have all been spot on and I was an avid opk ovulation expert. Took 9 months to get this baby so I did everything. My ultrasounds have been spot on too. Last one was at 20 weeks. Baby erasures 20 weeks. I was a little bigger when my midwife checked at 24 weeks but only by a week. But 26 to 30 weeks is quit a difference. My last baby girl was 8lbs. I'm having a boy. Maybe a big boy. I'm only 4'11 and I weigh 130 currently. So I'm not over weight either. Anyone else have this happen?