Could my Maternity21 test be wrong?

My result was a girl. I really feel this baby is a boy and all other tests said boy (wives tales, all in good fun). I sent in my ultrasound to The gender experts and via ramzi theory I got it’s a boy (They’ve yet to be wrong for me). I got the NIPT test done at 9 weeks 6 days. Is there a chance at my next ultrasound I’ll see that it’s instead a Boy? Really hoping for a boy as this is my 5th pregnancy and was hoping last if a boy. I have 3 girls and 1 boy already.