Talk to Gynecologist on Gender Prediction Ultrsound

I want to ask that my wife be 17 weeks pregnant. She went to the doctor for the routine checkup after the ultrasound, and the doctor did not tell her about gender properly and said that it might be girl, but she is not clear. She is also advised to go for the anomaly scan; after 2 to 3 weeks, they will give you a better picture of the gender. My question is whether 17 weeks are not enough. secondly, whether the breach position may change into a normal position; if yes, then how?