Welcome aboard, Cynthia! It is less than a month until you set sail on the Disney Wonder! You must be counting down the days! My family and I just sailed on the Wonder last week and got off the ship yesterday. It was an amazing trip, and I'm so excited for you to set sail soon too!
Disney Cruise Line offers bottle sterilizers at Guest Services should you like to borrow one of those for your use onboard. This will help with keeping those bottles clean while you're in your stateroom, Cynthia.
There are Pack n' Plays available as well. If you haven't already noted that on your reservation, give Disney Cruise Line (or your travel agent) a call at let them know you'd like to request one of those for your stateroom. Your stateroom host will set it up for you each night and take it down (allowing you more room to move about the cabin) during the day. However, if your little one will be heading back to the stateroom to take naps, you might simply let your stateroom host know you'd like it left up all day. They're very accommodating, so let them know what you'd prefer!
Children who are not fully potty-trained are not able to swim in the pools onboard for health reasons on the cruise ships, and swim diapers are not allowed in the pools. However, the Wonder has a water splash area next to the
Mickey Pool for the smallest cruisers to enjoy. Your little one is welcome to be there in a swim diaper and swim suit and splash around by Mickey's sorcerer's hat as little shooting geysers make for a fun splash area!
I hope that helps as you continue to plan, Cynthia! Please let me know if I can help with anything else before you set sail!