Gotta chime in here. December 21 sounds like a wonderful day to have a birthday. Mine's the 23rd.
I haven't read all the posts here, but my recommendation, as many have said is to be sure she has a BIRTHday. I can't tell you how many times I heard, 'go choose something from under the tree'. It was as if my having the audacity to actually have a birthday in the middle of the Christmas season was just such an inconvenience.
As someone else said, seems like a trivial thing, but all I ever wanted was for my BIRTHday gift to actually be a BIRTHday gift, with BIRTHday paper. Not Christmas paper because then it was a Christmas gift, and actually felt more like 'hush money' than a gift.
Now, it's pretty cool, though because I get the BIRTHday paper and everything. DH isn't so keen on it, though. He's not much of a shopper! LOL
Congratulations to you and your's!