Hi again, Amy! Welcome back!
Guests traveling with Disney Cruise Line to the Caribbean or Bahamas can view the
Travel Document information page on Disney Cruise Line's website for the most up-to-date requirements for travel.
As you'll see, passports are not required for U.S. citizens on that particular sailing (a state-issued driver's license and birth certificate will be fine), but I would highly recommend getting passports for all members of your party if you are able to do so in time. My family, including my children, always sails with passports as we feel more comfortable knowing that in the event of an emergency or health issue that prevents us from re-boarding the ship in a foreign port, we will more easily be able to get home. We keep our passports locked in our stateroom safe during the cruise, but carry them with us each time we disembark in port.
It's up to you, Amy. I know you are traveling with a large party of family members for your wedding and honeymoon, so the peace of mind might be worth the small hassle of obtaining passports before you set sail. However, you can certainly opt to bring just your driver's licenses and birth certificates (see the travel document page for further details).
Let me know what other questions you have as you continue preparing for this huge trip!