Hi Maureen!
It's a Small World! My son was 11 months old at his first Walt Disney World visit as well. He even took his first steps at a resort. And, while he is 20 now, he still loves the parks just as much as he did back then!
No worries, the Walt Disney World rules for
Outside Food and Drink are usually very accommodating. Plastic water bottles will be no problem to bring into the theme parks. While the water fill stations are great, I can understand your concerns, and, of course, the ease of carrying water with you is quite nice too. When your son would like to nurse, you can quickly and easily prepare his formula.
All of the Walt Disney World theme parks also feature
Baby Care Centers. These quieter locations are a great spot for a little quiet time - either for feeding or just some downtime out of the excitement of the parks. You'll even find a number of child specific items to make life easier: highchairs, nursing rooms and microwaves. These little conveniences make life so much easier with a little one!
I hope you have a great trip! It'll be here before you know it!
Kathie