Critique my graduation speech?

Hey, I’d love to hear some feedback on my graduation speech due on Monday. I’m not too great at speaking, so I kept it pretty short. Any advice would be greatly appreciated!

   Good evening. Although this may be the most that many of you have heard me speak, it is truly an honor to be here before you today to represent the class of 2017. It is hard to believe that we have finally made it to graduation day. After four years of sleepless nights studying, early mornings rushing to class, and weekends hanging out with friends, we have finally arrived at that long anticipated day. Graduation day provides us with the opportunity to reflect upon our high school experience, to thank those who have helped us along the way, and to look ahead to the future. Ultimately, today marks a time of change.

As I began to write this speech, I was overwhelmed by the multitude of memories that we've shared as a class. When we entered Twain High School as freshmen, none of us knew what high school had in store, but for four years we persevered. As high school progressed, we've expanded our knowledge of polynomial functions and the periodic table. We've memorized literary devices and the events of the American Revolution. Outside of the classroom, we've expressed our individualism through music, art, sports, and clubs. We've texted each other homework assignments and endured the crammed hallways. Each of us understands the struggle of running from the history hallway to the portables, the rush to complete an assignment due the next period, and the hope that the chance of freezing rain would miraculously lead to a snow day. While we have all come from different backgrounds and have taken different routes in high school, our common experiences have given us memories to look back upon. As we leave this familiar campus where we have all been forced to accompany each other for four long years, we will forever have Twain High in common.

Of course, everything that we have accomplished would not have been possible without everyone who has come here tonight to support us. The support and guidance of our families, friends, teachers, and the school community has helped shape us into the people that we are today. Thank you to our families, who nagged us to work hard and provided us with a much-needed support system. To our teachers, who taught us new information despite our reluctance and put in so much time and effort to ensure our success. And to the school community, which has pushed us to try our best and to "be the one". For all of your help and support, we thank you.

Finally, it is time for the high school chapter of our lives to close. For the graduating class of 2017, all areas of our lives are about to change. As we go forward we may forget the quadratic formula or the components of a cell, but we will always remember the memories we have made and the people who have helped us along the way. It is time for us to begin the next step of our lives. To quote our very own Mark Twain, "the secret to getting ahead is getting started". 

And now, as much as I am enjoying this public speaking experience, it is time for us the finally walk the stage and receive our diplomas. Congratulations to the Twain High School graduating class of 2017!

Sorry, I didn’t mean to post this twice!