@MrsP4, I can relate to this, but for having boys. I've not had a gender scan in the end for many reasons (one being to keep the hope of a girl alive that bit longer). I did, however, do the sneak peek that said boy and almost everyone has said they're sure my 12w scan is a boy. I'm holding onto the last bit of hope, like you, that they'll all be wrong and at 20w they'll say girl (I know the chances of this are practically 0!).
Unless you've been there, it's hard to understand how gender disappointment can impact a pregnancy. You're mourning the loss of an expectation, a picture, a dream that you'd built up in your head. I was convinced my first was a girl (lots of wishful thinking, I think) and was so upset when my bubble burst at the gender scan. Obviously I wouldn't change DS for the world and he's my happy, clever and loving baby and love him more than anything. It honestly seems so silly looking back because now I truely wouldn't have it any other way.
If I'm honest, I've slowly started preparing myself for them to confirm boy at 20w scan and have been saying it's for the best etc. when people ask, partly because if I say it often enough, I may start to believe it. What I do know though, is that when baby arrives I wouldn't have it any other way. I'll love them just as much as I do DS and it won't matter if they're blue with pink polka dots in the end because they'll be a very loved part of our family and that's the most important thing.