We've been on two cruises, both Carnival, two different ships, Western Caribbean and Eastern Caribbean. Had a wonderful time on both with no problems. I have Celiac Disease which is an intollerance to gluten, (it's in lots of foods) so I have a very specific diet to follow. All I had to do was notify them ahead of time and I was accommodated in every way possible. The hostess would come to my table and setup my dinner for the next night and I always had a wonderful surprise dessert every night. They even have a specific kitchen where meals are made for medical diets and people with food allergies only. We always found the staff to be courteous, friendly and very accommodating. Both our cruises were in the month of November and not a lot of children.
I hope your experience will be as wonderful as ours was no matter what cruise line you choose. Happy sailing!!!