can you not consider a private scan, a 3d one can be done up until 32 weeks i think and privately youll get more time to investigate.
I waited 9 months to find out the sex of my baby, you can do it if you really try and then go out and buy as many girlie things as you want if they were correct :)
Like I said, I've gone ahead and bought pink. If it's wrong, it's wrong. I always think.... the worst that can happen is that I'm having a boy and thats fab anyway! Just bought up to 3-6 month clothes, so not too much spent out on pink!