I am the same. If it’s a good book I will read it in a day or two. If not it will take me months. but I do love reading. I also personally love jigsaw puzzles. It seems like an odd choice for adhd but i can work with my hands (fidget) and think about other things in the world or day dream. I like the amount of thought I have to put in to the jig saw puzzle. It’s not completely mindless, but enough so I can think of other things too.