May 18 is the last departure date--she leaves for the trans-Atlantic cruise on that date with sailings in the Med to follow.
The, I think she's back in Galveston in the fall of 2013 after the dry dock.
I vaguely recall the article and reading DCL had contracted for 2013 and 2014, but was leaving early after 2013.Disney said once the last sailing for Galveston in 2013 was done, then their agreement was up with the port and they were leaving. Someone posted the article on the boards here a couple months ago. I don't think they will be back for 2014, they wanted to try new ports