Kara, xmas cards should not be something added to the list of things you're worried about right now.
Don't sweat it! I know I always get at least 1 card after xmas from someone who left it til the last minute, and I love it, because it's like a bonus! You think they all arrived and it's all done, and then Hey! Another one! Cool!
Even if you don't get cards out at all this year, I don't think anyone here is going to beat you up over it.