First, I want to say that I in awe of how well your family seems to cope with Sebastian's issues. I found a mass on my 5yo son's arm and about lost it the five days it took to get a diagnosis. It turned out to be benign but it was a scary situation. I know that your situation is not as carefree as it sounds when you write, and your family is my thoughts and prayers.
Second, I am just like you about the Disney planning craziness. I do not think there is a minute in the day I am not thinking about what were are going to do at Disneyworld and have much my children will love it. (Maybe I should write a pre-trip report too.) At the moment - I am designing "checking into the resort" customs for my family. I think I have gone off the deep end - but it is so much fun!!!
Third, your husband must be one of the kindest men in America. I love that he does the matching clothes with you and the kids. It takes a special sort of man to do that. I am also 100% sure that he is sick of talking about Disneyworld. My husband has vowed if I say one more thing - he will cancel the trip!!