Oh, we went through a few months of that too, so frustrating!!
I don't recommend pull ups - they are less absorbent than normal nappies imo.
Have you tried a bigger size of disposable - I went up a size at night only, and found that helped. I would not be limiting fluids, I would hate to go to bed thirsty.
I have a couple of sheet protectors that go over the top of the sheets that I used for toilet training (brolley sheets, but am sure there are other brands too). This means that I don't have to change the sheets all the time, just the protector.