I attribute every bit of it to the "pre-wedding" bit! What you're feeling doesn't seem to be too far from what most other people have told me they felt right before their own/their friends' wedding.
What I do when under stress is take deep breaths and think, "What can I do about it?" Usually I can't do anything. Yesterday I had to do jury duty, and I was getting really anxious about driving home from a not-so-pleasant, strange neighborhood. So I thought "What can I do about it?" Nothing. Either I drove home or stayed downtown forever. So I drove home, anxiety-free. If I'm nervous about an exam before bed, I'll say, "I studied all I could, and there's nothing more I can do about it" over and over until I believe it and fall asleep.
While a wedding is 9023842093430 times more stressful than most things in life, especially exams or traffic
, I'm sure the same principle can be applied. Enjoy your vacation! Don't even THINK about the wedding planning. Tell your bridal party (whom I'm assuming are your best pals!) your concerns, and have them spread that stress over all those people. If not them, I'm sure you can find a confidante to take over watching over the planning until you get back. Just go on your honeymoon and think only of those nice massages and cocktail drinks and romantic rendezvous with your fiance. There's nothing you can do to change, help, or fix what's going on with the planning at home, so enjoy your stress-free time! (Easier said than done, I know!!!) Good luck!