Believe me, I don't think there are many people who have been on JY holidays who can honestly say they didn't go through exactly what you are going through now. For me the first big hurdle was picking up the phone to book a holiday, I picked it up and put it down again more than once before I had enough courage to hold on. The next hurdle was to get myself to the airport, oh how I wished I hadn't booked that holiday. That was 2 short haul and 12 long haul holidays ago and I'm now looking at number 15 and 16 for next year.
Take a big breath, tell yourself "I CAN do this" and go ahead, once you get to the airport and meet everyone else you'll wonder what ever held you back.
I've been to China and loved every minute of it, a good choice. Think Great Wall, terracotta army, pandas, yeahh you're there, confirm!
Avocet