I'm level thirty and the game has got too easy for me (on Expert). The problem is there don't seem to be any high level monsters like the land dreugh or minotaur or the various high level daedra that start to appear when you reach a high level in Oblivion. All I've seen are the high end draugr (which I kill rather easily), one chaurus reaper and one dragon priest, and that's it. Even dragons are becomming a push over.

So am I just in a sort of limbo between easy and hard monsters or is that it?

No.
If the draugr deathlords are no longer a problem for you, Im afraid thats it.

Then I now know what I want most in the DLC.

Why not play on Master? I was pretty much destroying everything on Expert so i played on Master and died two times in a row fighting a Blood Dragon.

Yeah stuff stops scaling. HUGE problem.

Dragon Priests are a fixed level throughout the game so you could always try to hunt them all down. You also may be transitioning to the next level of enemies. My character is level 39 and I have yet to see very many Ancient Dragons. Also you may just turn the difficulty up.

I was hoping to avoid turning the difficulty up as I thought it would make the game somewhat unrealistic, that a simple bandit could be more powerful than the Dragonborn, but I guess I have no choice.

What the game definitely needs is super dangerous high end monsters.