Gender Disappointment

We just learned that we are having a little boy for our first child. After reading the results I broke down in tears. I know I'm being unreasonable and horrible...let me say that I am so glad my baby is healthy and am grateful that I was even given the chance to become a mother. And yet I still can't help that each time I think about it not being a little girl I break down. I never wanted a girl for the thrill of dress ups as I am a tomboy myself but I've always wanted a girl. I've even felt the level of excitement for my pregnancy drop drastically since I found out. Has anyone else experienced this? Is this normal or do I need to get help?? How long will this last?

Disclaimer: I am so very blessed thaty body was able to make me into a mother as I know a lot of women struggle. And I'm over the moon that our baby is healthy and am going to love him no matter what.