Welcome Aboard, Ashlee!
I can't imagine a better place to celebrate a birthday than aboard a Disney Cruise! Your daughter is going to love celebrating with Captain Mickey and his crew.
Your daughter falls into the "overlap" age for two of the Youth Clubs - Oceaneer Club/Oceaneer Lab and Edge. Oceaneer Club and Oceaneer Lab welcome kids ages 3-12, and Edge is for tweens ages 11-14. She's welcome to choose between the two clubs, but won't be able to go to both. I encourage you to have her visit both clubs on your first afternoon onboard and get an overview of activities and meet the counselors. Once she knows where she feels most comfortable, you can speak with the Youth Counselors to get her signed up for the youth club of her choice!
Before you cruise, check out the descriptions of the Oceaneer Club
here, the Oceaneer Lab
here, and Edge
here. She may decide ahead of time which one is right for her! My kids have participated in every club, from the nursery to the teen club, and loved every minute!
I hope this helps! Happy 12th Birthday to your daughter - wishing her a most magical voyage aboard the Disney Dream! - Diane W.