Assuming by 5/21 you mean 5/21/2006?
If so, you may want to review the department of state travel regulations - if I am not mistaken, you will need a passport to take any cruise that departs the USA effective 12/31/05.
Not sure how your name change will affect passports - but I'll bet some experienced cruises can answer THAT question (or folks at the local Passport office can for you).
Congratulations on your upcoming wedding - may you two have a great life together!
(Cruising on 10/9 on the Conquest with Wife & kids in celebration of our 25th wedding anniversary