Once you get home, you will laugh at yourself, for worrying so much!!
I just traveled from Ohio to Las Vegas and back without incident. Not my first trip away and I've gotten into my routine for traveling.
I carry a change in my purse (I do any cutting of products at home) in a plastic bag with paper towels to clean, if needed. I also carry all supplies in my regular carry-on (and will usually check them on the way home if I have checked luggage). I have not had to
open my purse or carry on for TSA to inspect (knock on wood!). Bring extras but you don't have to go overboard. If you change once a week bring 3 or 4 changes. I do wear a two piece so I bring bags for everyday plus a few...I like to have a clean bag that I don't have to dry especially when at the beach.
I have never let TSA know that I have an ostomy and I've never received the 'extra' treatment. I do empty right as I get into line (not sure if that helps or not) and usually get pointed to the full scanner line...my friends usually get the pad-down!!
As far as hotter weather/swimming goes, I use Sure Seals and have never experienced a shorter wear time when swimming. I also change once a week, even when away, which makes planning easy! You may want to work your schedule so you change the day before you go (if you'd make the whole trip without having to change) or plan to change a day or two into your trip so you know you'll have piece of mind on your way home.
Most importantly, have fun! Eat, drink and enjoy your family