I appreciate your response and I understand that it's difficult to predict. However, remaining flexible introduces some "financial complexities," so I have to be doing my best to predict and plan and best guess as best I can.
For example, suppose we can't check in on Tuesday as planned due to a hurricane warning, Disney will refund us and help us move the date. However, if we move the reservation by even one day, we lose free dining *and* have to pay rack rate for the room, since all the September offers have expired. For us, that means the same number of nights, tickets, etc. adds an extra $1,600 to our cost. That is not at all insignificant.
I wish I could not be worrying about it, but I can't help it.