36 week ultrasound.

Ultrasound said my babygirl is weighing 6pds 7oz they were worried thinking i was going to have a small baby. My son was 8pds 9oz. She said usually with your second baby they are usually bigger i dont know if i believe that or not. But i weigh 141 right now at 36 weeks 1 day I was wondering how much bigger my baby will get? Due march 5th.