I feel like I'm forgetting something?

Relax, it sounds like you have everything. I get this same feeling on every trip that I go on and usually if I do forget something, its trivial. (like a shirt or something) Being that this is such a big trip for you, its natural that you are going to feel like this. Make sure you have your carry on bag and pack a extra pair of clothes in there. (In case your luggage is lost) Then you will be good to go. Good luck and have fun!