My son and daughter in law cruised for their honeymoon last year. My daughter in law was only 20 when they went. Just make sure that your reservations (air and cruise)are made in your maiden name as you won't have time to have your ID changed. All they had to do was show their copy of their marriage license with all the signatures on it. They did not have their certified copy back from the state yet either.
Make sure that Carnival knows that you will be a married couple when you make the reservations.
Congratulations on getting married and let EVERYONE know that you are on your honeymoon!!! You can get free stuff.