First of all, congrats on the weight loss!!! I love what you said...it's not a "diet", it's a lifestyle. That's so true...I cringe when I hear people say they're going on a "diet". DW and I are both very much into health/nutrition/bodybuilding. It's definitely a lifestyle for us, especially her. She's about 95% of the way to being ready to compete on stage. We both have low carb diets. Her nutrition is so specific that she weighs and measures everything that goes in her mouth. Even salads are weighed, and almonds counted down to the last one. We don't eat in WDW restaurants, we bring all of our own food in. Partly because I'm cheap, partly because of our nutrition. We don't bring our food scale with us, so we can't measure everything...though we're so used to it we can guestimate pretty darn well. Certainly since it's vacation we allow ourselves to cheat somewhat on that lifestyle...me much more so than her.
I still eat a healthy base of foods, but I'll eat plenty of chips, desserts, ice cream, etc...just because I want to. DW sticks more to her nutrition, but will eat some ice cream, will grab one of the kids (or my) chips, etc...
We were just in WDW for 2+ weeks. I gained a little over 6lbs while on vacation (I intentionally had dropped 7lbs before we left), and DW gained about 6lbs also. I know, it sounds weird...she gained as much as me, and I "cheated" far more than she did. Every human body is different...my metabolism is higher than hers naturally. Yes, you do a ton of walking and that will definitely help. But we don't burn as many calories walking as we do in the gym every day, so there's that factor. Plus, it's so hot that we hydrate a lot.
However, there's a huge silver lining here. If your normal lifestyle is very low carb and you never normally do a cheat meal or a couple of day "re-feed" for your body, it kind of goes into starvation mode (which can limit weight loss). So when you suddenly throw in extra calories, especially carbs, it can cause your metabolism to spike as the body tries to cope with the extra calories. I lost 3lbs within the first week home, and DW lost 7.5lbs in the first week home...so she actually weighed less one week after vacation than the day before.
So my advice is to just enjoy yourself. You're on vacation. Want to eat a treat? Go for it, enjoy every bite. As long as you return to your healthy lifestyle when you get home, you'll be fine!