My daughter HATES

crowds also (and lets everyone know it) so we never go when it is crowded. I can't add anything to the days to go but for inside DL I have a couple of thing that help us.
Don't shop at the end of the day - the stores in DL are crowded then. DTD stores get crowded at night.
If main street is crowded (or just more people then you like), and it is not the end of the day, you can walk thru the stores on either side to get to the end of main street. The right side you end up walking out of the store for a few yards.
Look at other ways of getting to where you want to go instead of the most direct. They usually don't take much longer, there should be less people and you might find something that alot of people miss.
If you are waiting in line, for the parades, or fireworks, carefully placed things (including family) can get you more space.
The are a number of area to get away from people and recuperate.
If the area you are going look to crowded, go somewhere else and come back later. We always know what we want to do but never make a list so that we can change where we are headed without anyone feeling disappointed.
Have a wonderful time!