I know that it is difficult, but relax. If you forget anything, you can always buy it. I'm guessing that you are renting a car since you will be in a condo or is it DVC? In any case, even if you have to go offsite, you can always find what you need.
That, and bring at least 2 pairs of shoes per person. If one is really painful, hopefully the other won't be. That and clothes are the really important things!
BTW, I way overpacked with disposable supplies. (Diapers, wipes, hand gel, etc.) DH was making fun of me by the time we left. I understand about stressing about packing and how difficult it is to relax. After our trip, that is my best advice, and, hopefully, I will next time! (It was also our first family trip and first time on a plane with kids. I understand the stress!)