Oh, Bolly. Yes, yes, and yes. You're really not alone with this.
We found out last week we're having a boy. We already have a daughter. I had a perfect girls name (that I'll never be able to use - goodbye Margaret Verity Ellen). Since finding out it is a boy I've been really quite flat about it all. I'm not interested in thinking about names either.
Do you want to know something ironic? I had a very similar reaction when I found out DD was going to be a girl 5 years ago.
It's very normal. You have an image in your head, whether it is an image of a name, or a baby, or even of your 14 year old child. And then that image is changed.
All I can say is that look at it happening twice with different genders - what does that tell you? You really do fall in love with the child you get. I didn't want a girl, I got a girl, now I can't imagine having a boy.
Don't stress yourself too much about it. It's completely normal x