Hope you meant Sept 11th - the Miracle sails out of Tampa on the 11th, so if you don't show up until the 12th you'll miss your ship!
I'm on that sailing and watching the Carnival website for any possible changes, but unless there is another hurricane out there I don't think we'll have a change.
CarnivalSensation February 2015
Carnival Dream November 2015
Carnival Fascination April 2014
Carnival Elation March 2011
Carnival Imagination Sept 2007
Carnival Sensation Dec 2006
RCI Sovereign of the Seas Sept 2006
Carnival Miracle Sept 2005
Carnival Glory Sept 2004
Carnival Fantasy Jan 2004