Were you married in the same area where you currently reside? If so, you should be able to go to the courthouse and get a certified copy of your marriage license. Even if you were married somewhere else. often all it takes is a phone call / fax and a few dollars and they'll send it to you.
I have a passport, but have my marriage license paperclipped inside my passport, because my passport is in my maiden name and it doesn't expire for two more years. The person you spoke to at Celebrity gave you good advice and is correct that you need to have official documentation to explain the name change. They may not ask for it, but I wouldn't take the chance.