It's perfectly normal to be nervous when your scan's due, i was convinced it was a boy too and she's a girl! To get my head round having a girl i went straight out and bought her first dress and now i'm really excited about my baby Belle!
I don't think i breathed at all during the scan and they can take a while before they say anything so don't worry when the scan person's quiet cause they're looking and concentrating on measurements before they tell you anything.
Good luck and go and buy something girly if it's a girl!
