You are reading mainly college textbooks? If so, I think that's normal. I had to re-read every text book when I was in college. College text books are full of information and it's not easy to get the full meaning of what's written most of the times. I was an engineering major and had to read physics and math books countless number of times. Same thing goes for the liberal arts stuff like psychology, etc. And carrying five courses at the same time is very hard. I had a semester where I had lots of trouble taking tests (very easily distracted) and got two Ds, two Fs. Next semester I took a medical leave of absence for my mental disorder.