It's hard not to think about the birth even this early. This is my second time around and I am thinking about it already.
I brought a ton of stuff the first time including things to sleep in and didn't end up using most of it. You will have bleeding, and it was just easier for me to wear the hospital gown and get checked out all the time. Plus, I didn't ruin any of my clothes. I wasn't exactly jumping in and out of bed a lot and I only stayed one night.
Things I did use were: camera, my own pillow, clothes/blanket for baby, outfit for me for going home, clothes/pillow for dh, and toiletry items. That's all I can think of.
If you take a childbirth class, they explain almost everything and go over things like this.
As far as your Hospital stay goes, you might want to take your own gowns, just so you don't show your bum to everyone :) but remember you will be checked (gowns not jammy pants) and there will be heavy bleading so don't wear expensive stuff, nor white! Don't worry ;) it will all come to you, just remember no need to pack the whole house! I'm more excited about packing the baby bag!
It's so early at the moment, I really wouldn't worry yourself thinking about the birth as we have many mountains to climb before that! Just relax for now and worry about that nearer the time... Good luck with it all!