Welcome aboard, Luigina! It sounds like you'll be setting sail on the Disney Fantasy next month! What a treat!
Since your itinerary won't be stopping in Nassau, you will not be able to visit the Atlantis Resort. Castaway Cay is in the Bahamas, but not close enough to Nassau that Port Adventures are offered going there. However, keep in mind that if you ever book another Disney Cruise, there are many that offer Nassau port stops and Disney offers quite a few Port Adventures in Nassau that head to Atlantis to take part in many of the activities there. If you're looking to re-book another cruise, consider doing so while onboard the Fantasy. Special discounts and incentives are offered to guests who book while onboard the ships, Luigina!
The
Bibbidi Bobbidi Boutique is so magical on the Fantasy. My daughter still talks about her visit there when the Fairy Godmothers-In-Training transformed her into Snow White! I'm sure your daughter will love her experience there. The sizing for the costumes runs about the same as the sizes that are sold in the Disney Store online. A small is a 5/6, Medium is 7/8. For example, take a look at the
Belle dress at the Disney Store. Click on Size Chart, just above where you select a size, and you can view the specifics on measurements. Hopefully that will give you a better gauge of what to order for your daughter's magical makeover on the Fantasy!
Happy planning, Luigina! Please let me know if I can help with anything else before you set sail next month!