If you want it to be 'worth it' you first have to define for yourself what makes the vacation worth it. If you know what your goal is, so to speak, you can look for ways to achieve that. Most likely your goal for your vacation is to have a good time with your family, and how you achieve that is up to you
be realistic about what happens if you don't achieve a certain part of your plans. Would not doing a ride, or missing a show, or not going to a specific restaurant truly influence your 'worth it'?
For your anxiety, think about what is it you need if your anxiety is getting to you. What would you do if it happens during your every day life? Do you need some time alone, or just sit and rest. If music gets you back to Earth, make sure your phone/ipod is charged and filled with your favorite music and a pair of headphones.
What I experienced usually helps, is to make a list of all the situations that might make you anxious and what you can do about it. Then you have a plan. And something to add is the probability something might happen. The things with the highest probability need a plan the most. Like an agry mob in the morning running all together to FoP. You can avoid the mob, by having a fast pass later in the day, or let the crowd pass and accept a little longer wait in standby, go to the ride during the evening show etc. every situation can be tackled in several ways. The more solutions you find, the better.
You are with 5 adults and 1 child. So, there will always be someone to look after the child (not sure if it's your child), so that shouldn't be something to worry about.
Also, discuss it with the others, if they know what you might be going through / are anxious to face certain situations, they might be able to help you, by just holding your hand, or talking to you, whatever you need. But you need to be the one to be open about it for them to help you. Even when they know you are an anxious person, it doesn't hurt to remind them.