I am also in university and struggle with reading too. Some of my readings can be very difficult to comprehend, especially research papers. Sometimes, hearing spoken text helps me understand. Have you considered trying text to speech software? It works with pdf, word and text files.

Reading out loud has also helped.

Are you interested in your courses? Boredom may be a part of it. Where are you reading? Could the environment be contributing to the problem? What about lack of sleep?

Regular reading improves comprehension, speed and concentration.

Reading shorter books is certainly a good way to build up confidence.