Essays / Ideas on a Narrative Essay on a mistake in my life. [4]

this is what i have so far

Many people make mistakes in their lifetime. A mistake I made was not taking high school seriously and not doing the best I could. My grades in high school were almost like a roller coaster, going up and down. When I started high school I had all honors classes. Thinking that the classes would be very challenging and strenuous I tried to do the best I could. I did all of the homework, took notes, studied for tests and paid attention in class. When the first trimester had ended, i was happy to find out I had received high grades in almost all of my classes. In the middle of freshman year i stopped working so hard because everything i had so far didn't turn out to be as hard as i thought it would be. I started joking around in class and studied less often. My grade in history went from a 95 to a 75 in one trimester. I was still able to pass without any problems. Summer came and I was out partying with friends almost every night. When sophomore year started I started struggling with classes such as math and chemistry. I wasn't getting high grades like I did in the beginning of freshman year. I was receiving from average to below average scores on tests as having a satisfactory grade point average. I still tried hard in school but not as much as I did in freshman year. Then end of the year had come and i had barely passed all of my classes.

This is about a page so far and i guess ill write about my junior and senior year for the rest, which will pretty much sound the same. Does it sound like i am saying "I" too much? Besides any spelling mistakes is there anything i should change so far?