I'm sailing on this ship/same cruise on May 21st. I expect you will see fewer school age children on this cruise, althought toddlers/infants will be plentiful. This will be the 4th NCL cruise for me and I always see a broad age range of adults, but most on this line are 40 somethings. I suspect a lot of homeschool families choose your same timeframe to avoid the crowded children's programs and possibly because the price does go up beginning Memorial Day weekend.
You'll have a great time!