Well, first, I hope you don't avoid the bathrooms completely?
Okay, really, it's not necessary to "bring your own" soap, and water(!). If you are concerned about germs on the faucets/dispensers, simply use a paper towel between your hand and the faucet to turn on/off the water, and on the soap dispenser to, well, get soap.
Your kids wearing their gloves everywhere is only effective if they don't touch their faces/mouths with their gloved hands, or put any food in their mouths that they've picked up with the gloves on.
The sink water vs. bottled water thing again, but this time for your sister's teeth? WHAT do the two of you think is in the water supply at Disney that is so dangerous???
As for sleeping on the couch? Ugh. Not without clean bedding on in, and then what's the point of being scrunched up on an uncomfortable couch when you can be sprawled comfortably in bed (unless, of course, the bed is too high to get into and you're short enough and THAT'S the only reason for sleeping on the couch).
Bring your own sheets? Okay, but really, the linens on your bed when you check in ARE clean. You'd do better to worry about the blanket, the bedspread, and the pillows.
Yes, you're both a bit overboard. You can't develop antibodies to something if you're never exposed to it. Were you healthy as children? Are you both healthy now? Were your parents this germophopic when you were growing up? I'm betting they weren't, and you grew up just fine; in fact, that's WHY you grew up just fine.