I see you are going on Valor??
We cruise with my Brother in Law and he is on Oxygen!!! We drive to the port and take all his oxygen bottles and his compressor(what he uses at home) and have no Problem getting on Carnival ships.
No problem with customs or security getting on or off the ship. And we got head of the line privilages since we were carrying the compressor and oxygen bottles with our carryons.
He has rolling carts that holds several bottles so its not that big of a deal with the 4 of us each taking one.
Enjoy your trip!!!!
Our next Cruise is May 1 on Conquest!!