Julie, I'm sorry that you aren't having the greatest time right now.
I know that it will cause arguments between you and your family, but if moving to an apartment is really what you want, then you have to tell them that, don't hold back because of what they will think. You deserve to be happy and if it's what you want, then you HAVE to tell them.
About the Christmas 'spirit' I'm not feeling really Christmasy this year either. I haven't been for the last 3 years.
For me it's because the time just goes by so quickly, there really isn't much time to get into the spirit of Christmas, one minute it's months until the 25th, and the next it's already over!
It sucks, and my birthday is on Christmas so it's not that great.
But just take some time out, and listen to some Christmas carols