20 week scan left me feeling low..

so I had my 20 week scan on Tuesday and we were told we're having a baby girl. i was so excited (I have a son from a previous relationship) and I was winding my partner up about having to buy pink clothes ect as he was 100% it was guna be a boy, we're also both alternative in our styles and he has a 'don't mess with him' reputation (purely because he's 6ft 2" and bassically pure muscle) in reality he's as soft as a teddy bear. Then out of the blue the lady who was doing our scan went on a whole rant about how we shouldn't get to excited and buy to much pink as they 'sometimes' get girls wrong and because I am carrying extra weight it's harder to get a clear pic (altho through the whole scan she was saying how perfect the pictures she was getting were) so now I'm struggling to enjoy the fact that it's a girl incase it's not. I'm just feeling deflated about the whole thing because of the way this woman reacted..