I was able to get one when I was offered an upgrade, I had to pay a bit more but was able to book a room that holds 4 people, for just my son and I. I am hoping he'll like sleeping in the bunk so I can have the big bedI do wish they would let you book the bigger cabins for just two as well, but I suspect it is because most do not sleep more than 2 (unlike Disney, from what I can tell almost all their cabins sleep at least 3 people). At least on Carnival the beds do separate. I don't know about you but my son is miserable to share a bed with! So while I do have to sleep in a twin, at least I don't have him kicking me or pushing me out of the bed. Of course it's small enough I feel like I'm going to roll out any way.
I offered to move to a higher category room but they still wouldn’t give me a room with what I want. I’m like you with my kid. I’d rather suffer in a twin than fight for bed space