Doctor is 100% sure...

I don't know how much I believe the doctor. He told us we are having a girl and he's 100% sure. Part of me feels like he's gonna tell us next appointment or the one after that, that's it's actually a boy. Maybe I'm just worried about painting everything pink and buying everything girly and then 2 weeks before birth being told it's a boy and having to change everything (I've had a few friends who had that happen). Or maybe I'm just worried my husband isn't as happy about a girl as he claims to be. He says he's happy but hasn't shown any interest in helping me with anything baby girl related.