Baby's gender

Hi, im 21 weeks pregnant and just went for my antenatal scan last 2 days. The sonographer said she sees a baby girl bcuz she did not see any penis and claims according to the thigh bone it looks flat. She said usually its bout 70-80% accuracy. But how accurate is it cuz she didnt confirmed at all. Im planning to start preparing for the arrival of my baby. Hubby wants a boy... MIL wants a girl. And im not even sure of my baby's gender! ? anyone pls??