I don't have any advice about WW but I always wait a few days to weigh myself after I get back from WDW. I find all of the food at WDW to be very high in salt which makes me retain water. So I always end up coming home very bloated and up a few pounds because of it. If I wait two or three days after I get back I typically find that I weigh a few pounds less than I did before I left. All that walking really helps. So if you come back and your weight is up, don't panic - give it a few days and then weigh yourself again.
Other things I do:
I don't freak out over what I eat. If there is something I really want I get it - it's vacation. But I don't get things I can easily get at home. I'm not the person who gets an enormous 2000 calorie Starbucks drink on Main Street when there is a Starbucks on every corner at home; the calories just aren't worth it to me when there are so many other yummy options at WDW. We don't eat at Rain Forest Cafe or Shulas because we have those at home as well.
Familiarize yourself with all the menus before you leave, that way you can pre-plan what you want to eat.
I am not a breakfast eater so I typically don't do breakfast but do an early lunch at around 11:00.
I always remind myself that I don't have to snack just because I am at WDW. There are very few sweet snacks that are appealing to me so before I eat anything at WDW I always ask myself if it is really worth the calories to me. It's why I don't like the Mickey Bars - they are just chemical tasting fake vanilla ice cream and basic low quality chocolate. The fact that it is shaped like Mickey doesn't change the fact that I would never choose to eat something like that at home. And contrary to what everyone says on
Instagram - Mickey shaped foods do not taste better.
I also remind myself that I will be doing a ton of walking in heat and humidity and that it is super uncomfortable to tour the park if I feel stuffed with food. This helps me stop eating before I get full.
My DH and I will typically share something as opposed to get our own. This allows us to consume less calories but also allows us to try more things than we would if we were each ordering our own item.
I always feel much better in the heat if I drink a lot of water, plus it fills me up. I actually drink a bottle of water at least every hour during the hot months (yes, I also know the WDW restrooms very well!).
My DH and I tend to take our time in the parks now that we are building a house near WDW and know we will be there all the time. On our last two trips we got up and walked in the mornings before getting dressed to go to the parks. It allowed us to walk faster than we do in the parks so we burned some extra calories.
You will be just fine. Have fun! Congrats on your weight loss so far!!