There are some interesting discussions in "Birthparents Trying to Conceive" forum about this specific issue.
I made a post (
Petrified of a Girl) in which I stated that I was absolutely petrified of having a girl. (My first child, placed, was a girl.) Your feelings are not uncommon or unwarranted. I am due next month (though currently on bedrest and looking to go earlier than our due date) with what will be our first child post-placement. (Husband was not the first child's birthfather.) I have been through a myriad of emotion, trying to figure out what to do with this child, how I will feel, how to be a parent, etc.
There are lots of women around these parts that have had a child post-placement that have helped me through some of these questions. Do not feel alone.