I ended up answering my own question. After leveling up a couple more times, it became apparent that Expert and Master aren't really any harder than Adept most of the time. The game is just easy, that's the way it is.
The only thing that turning up the difficulty REALLY does is change the occasional tough boss fight into the occasional "I just got one-hit killed and my last save was an hour ago" smash-the-TV nightmare.
Also, I think I discovered that playing on a higher difficulty made at least one part of the game WAY EASIER. It appears that changing the difficulty doesn't just change the damage output of ENEMIES but rather ALL NPCs. I was in Riverwood when it was attacked by a generic dragon (it didn't have a name, it was just labelled "dragon"). I couldn't force it to land because my bow just didn't do enough damage. As I stood there contemplating what to do next, three Whiterun guards showed up with their bows and I watched in horror as the dragon's ENTIRE health bar disappeared in 3 large chunks. 1, 2, 3 - he was dead in less than 5 seconds! ****ing Whiterun guards stole my kill!