Having worked on ships my entire adult life (and I'm far older than you), I can understand your situation.
Here are some bits of info that may help you:
Travel Agents are our biggest allies. They do most of the sales work for us. We will make any effort or sacrifice to avoid competing with them.
Our Corporate Offices are not set up for high volume sales. We will sell cruises there, but would prefer not to - especially if it is seen as competing with our travel agents.
We could spend many millions of dollars to construct sales centers, hire and train many thousands of sales agents, and fill our ships. But guess what? Our ships are already full, frequently with long wait lists. Our travel agent partners are doing it for us, and we only have to pay them small commissions. We don't need to compete with them, and we don't need to spend those many extra millions to do it.
Experience has shown us that employees working at home are not very productive. Did I mention that we do not want to compete - or appear to be competing - with our travel agents?
We do have sales agents working on our ships, but they are required to be very productive, are not paid commissions, and their sales (and resulting commissions) are usually transferred to the passenger's travel agent. I think you can guess why.
My company has nearly 20 ships in the fleet sailing itineraries all over the world. I have a very good friend who is currently a very sucessful travel agent, specializing in cruises.
She has taken hundreds of cruises on nearly every cruise line out there.
She has the same dream as you. She wants to work on one of our ships, selling cruises.
I can randomly name for her a cabin on any of our ships.
She can tell me the category of the cabin, the location on the ship, the layout, amenities, plusses and minuses of that location, pricing, and can usually give a better recommendation for the same price.
She can also tell me the ship's itinerary, with extensive port information, and can tell me if/when the ship will relocate.
She can also tell me when the ship had it's last drydock and when the next drydock is scheduled.
All this info come off the top of her head, with no assistance.
She can also compare ships and cabin categories between all the major cruise lines, giving accurate numbers to let you compare the differences.
My company won't hire her for sales, claiming she does not have enough knowledge or experience.
How do you compare to her?
If you really want a job like that, you will probably need to do an amazing amount of homework, and spend a great deal of money to experience all the different offerings.
Then you may get a chance (as she eventually will) to work onboard a ship 12 hours a day, 7 days a week, for a very small salary.