Yeah, that's sort of my life.
I'm a worrier, obsessive type. But I've been on and off Paxil for years, and that seems to help a little. I've tried all sorts of things to just get my mind off of things. Sometimes they work, sometimes they don't. But one thing that helps is sometimes just thinking through the situation. Going to the worst-case scenario sometimes helps me to put it all into perspective.
So, if your reservations are screwed up, what will happen? Chances are you can still get a room in the hotel and if not that hotel, another one. And hey, it is Jamaica, right? You wouldn't freeze to death if you had to sleep on the beach, would you?
Now, stop worrying and have fun!