Eh, I doubt it's a disorder. None of those books you named are particularly light, easy reads. I remember it taking me a while to get into Lord of the Rings (I was 15 when I read it, 29 now), and even once I was finished I'm not sure I had a full appreciation for the writing style. It's one I plan to go back to. Whereas with Game of Thrones/ASOIAF, I loved the first 3 books while taking a lot of time with them, trudged through the 4th and DNFed the 5th.

Like others have said, maybe try a less ambitious undertaking and see if you like it. I know it's one of the go-to books to name, but I read the first Mistborn book and loved it, and I'm currently on Well of Ascension (book 2). It's just deep enough with its lore/magic system but not extraordinarily complex or heavy, for me at least, and the writing helps with that.