Lost in Writing

When I'm writing on a certain topic, I am uncertain as to what the topic is about and what the instructor wants out of my writing. The feeling of confusion with my writing skills comes out from not having confidence in myself. In high school my teacher would make us write on the books we had read during the school year. While writing my essays I did not feel comfortable with my ideas or answers to the topics. I felt that my ideas were not as in depth as all the other students in the class. The other students would analyze the readings to make their writings much better than before. I did not know when or how to analyze the work and if my work would be correct to the teachers wantings.