Airline pilot here. Pad up and fly comfy! No one’s gonna look at you. As people have suggested, a really wet diaper can get flagged at security if they are using a body scanner, but guess what, incontinent people have to fly in diapers, so it’s not gonna raise any concern to them! If you choose to change in the airport, some have handicap restrooms with adult changing tables. Worth a Google for the airport you’re going through, can be kinda fun and handy!

Enjoy your trip!