We were on the Carnival Miracle in Jan. I canot eat meat, dairy products or eggs. I had the travel agent notify Carnival ahead of time and I went to see the head waiter after we boarded. I have been on 11 cruise on five different lines so I have some experience with this.
The head waiter did confirm I was in the computer system with special diet needs. So far so good. However we were stuck with a waiter that did not speak English well and I had diffculty trying to tell him my food concerns. They have a dining room hostess (like a head waiter) and she was to coordinate things for me but she did not do well either. After the second day I asked at the Pursers desk to see the Maitre'd but he never would see me.
I did get out of the Dining room hostess that most things on the ship are bought premade and heated to serve. Salad dressing all had dairy in them (must get the 55 gal drum size for the week!) I ask for no dairy dressing to be made but this had only limited success. I had them make Indian food for me and most of it was good. Buffett was a bit of hit or miss as it was hard to tell what was in some of the items. They do have veggie sushi starting at 4-5 PM on deck 2 for a couple of hours The pizza guy will make a non dairy pizza. They do have veggie burgers and fries.
You will be okay but I wouldn't say the ability of Carnival management on this ship when we were there to make adjustments is not great. Perhap if they have a change of chef or Maitre'd you will be okay. I do remember out assist waiter saying they won the Carnival "eagle" award for the best ship in the fleet, (you will see in the atrium) and the management was very harsh on the crew trying to win this award. He couldn't wait to finish his contract and move on to another ship!