I'm exactly the same! I have no preference or anything, but it would just be 'weird' for a few moments if she came out as a boy while you've been preparing for a girl for 20ish weeks.
I had the feeling we'd be having a boy too, but at the 20 week NHS scan we got told she's a girly. Then at 25 weeks we had a private 3D scan and there it was confirmed that she's a girl, without the scan lady knowing what was said at our NHS scan.
Still every so often I panick completely and think it's gonna be a boy! It's so silly, because I know it won't happen, but I can't help thinking: But what will I do with my purple baby room full of butterflies and all the pink/yellow/purple/flowery/bunny clohtes I bought! I don't really tell my husband anymore, because he's so down to earth he doesn't worry about anything and just looks at me like I'm a nutter
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If the sonographer at your scan was certain she's gonna be a girl, I'm pretty sure you have nothing to 'worry' about!
Anyway, don't really have any awesome advice, but just wanted to let you know that you're not the only one! Either way, I hope we both have healthy little babies, in the end that's all that matters!