Undergraduate / 'Kimberly, Margaret, and I' - Common App reflection - topic of your choice [2]

So I got an idea for an essay topic but it doesn't fall in any of the common app prompts.
Is this okay? Any feedback is welcome! Thanks.

Every morning, for the past six years, I have walked to school with two girls, Kimberly and Margaret. And every morning, I rediscover what it means to have true friends.

The three of us met because of a fateful 6th grade homeroom class. We all verged on painfully shy, and weren't introduced to each other until our parents denied us transportation to school, forcing us to befriend each other in an attempt to avoid the depressing isolation that would inevitably result from walking alone. Thankfully, 6th graders are quick to befriend, and we became inseparable.

In middle school, as avid bookworms, we would often discuss books on our way. Our book of the week ranged from the beloved Harry Potter series to the more grown-up Pride and Prejudice, and our opinionated minds each had something to contribute. I argued with Kimberly on the merits of each House in Hogwarts and sympathized with Margaret on the questionable societal norms of Jane Austen's 18th century England. On the rare days when we had exhausted that week's worth of discussion too soon, we would count the numerous snails on the sidewalk and cocoons on the fences, and delve into the wonders of biology. It was from Margaret that I learned about amino acids, and from Kimberly, the difference between a bacteria and virus. Even as twelve-year-olds, we shaped each others' views of the world and acted as defining influences.

It was in our freshman year that we started a new discussion. Perhaps because we were all searching for our identities, we tried to symbolize our personalities through random categories. I was indie electropunk music, because I apparently had the same subtly intense quality it did, the color wine red, which implied maturity with a hint of sass, and a spider, which had many eyes in which to view the world from different perspectives. This pastime offered not only personal introspection, but a glimpse into what others saw in me. Other times, we connected through music - Kimberly played the violin, Margaret played the clarinet, I played the saxophone, and we had all been classically trained in piano from the age of 5. We conversed about the expressive beauty of Beethoven's tragic melodies and Wagner's soaring fanfares while trying to pinpoint what exactly about pop music made it so popular.

In junior year, with the SATs approaching, we each vowed to share 5 obscure vocabulary words each day in hopes of conquering the critical reading section of the test. Together, we learned over 300 terms. Our work paid off, as a year later we all became National Merit Semi-Finalists, and our shared victory made it all the more glorious.

Today, I realize how crucial Kimberly, Margaret, and I were to each other. We taught one another the joys of learning, of opinions, and of knowledge. We proved how working together to accomplish a mutual goal could achieve extraordinary success. But most importantly of all, we showed each other the invaluable, eternal resource of friendship.

500 words