my essay is approximately 430 words long.
Well, did they not tell you how long it should be? If they did not tell you, they deserve to have to get phone calls from hundreds of students asking them how long it should be, so give them a ring! :-)
You should not have to wonder if it is too short or too long. They should tell you what they want. You could write 100 pages if that was what they wanted, but they should specify.
As I walked across the auditorium stage, I knew I had accomplished something spectacular. The plethora of monotonous----I think there should be a rule. You have to tell the reader some key piece of information about what the essay is about BEFORE using any big words. Let's not make the reader wrestle with plethora and monotonous... all these adjectives... until AFTER we give them an image of what is happening:
National Honor Society... junior year.--- These are the magic words that tell us what is happening. Can you put these sentences closer to the beginning of the essay? Give them these words to reveal what the essay is about, and that way they can appreciate the cool writing style you have in that first paragraph. We appreciate everything more when we know what is going on (just like when a song becomes familiar to you and you have it memorized and love to listen to it).
At the end of the essay, the theme is cheesy. If you want to use that theme, you should mention it in the beginning of the essay, too. But I think you need to make it more specific and unique in order to avoid cheesiness. I hope you don't mind me calling it cheesy; I write cheesily all the time.
Try to show that the decisions you made in high school were based on a philosophy of working hard to give as much as you can during this lifetime, and show that you are in the process of making a big splash in the world. Make it so that all your sentences are... sort of like... about the same main idea. Make it so that you introduce a great idea in the intro, and then the rest of the essay explains it.