I'd try Disney Cruise Line. I've interviewed their personnel and they said they try to work with special needs children. While they can't give any child one-on-one attention, they said they try to accommodate special needs when possible.
Only thing, though, is that kids have to be 3 yrs. old and potty trained to be in their youth program. However, since she's still crawling, I'd suggest you still try Disney but use their Flounders' Reef nursery. (The nursery is for those 6 weeks to 3 yrs. old, as well as 3 yr. olds who aren't yet potty trained.) You have to pay an hourly fee for this and it isn't open all day and night (but it is open daily -- you have to reserve your days/hours whenyou get on the ship). The personnel are wonderful -- I used it when my son was 7 months old. They will be able to give your child more personal attention and have plenty of toys, Disney videos, bouncy seats, cribs for naps ,etc. Really well equipped.
Let me know what you decide.
Luisa Frey Gaynor
Family Cruise Editor