She has no right to do that if there is more the 1 person who does the scan i advise you to tell them she has no say in YOUR pregnancy I wouldn't have walked out of there if I were you I would've demanded to speak to someone not really telling you to make a scene but you should have spoken to someone while there even another ultrasound tech tell them u want to know the gender and she dosent want to tell you so can someone else scan you
Your doctor should be able to tell you. The scans are sent to your doctor so I would call your doctor, or if you have an appointment coming up, mention to your doctor what had happened, and just ask your doctor to tell you.
I definitely would have said something to someone before leaving but as others have stated your doctor should be able to confirm gender visit the scans.