I had several students contact me after admission decisions were released this past April. These students had been denied almost everywhere, or had no acceptances at all. They sent me their essays, which were basically dreadful. What you think is great might in fact be a deal-breaker. I strongly advise you not to submit essays that haven’t been at least read by another, impartial person. Ideally not a parent, and certainly NOT a peer. Sorry to say, but other teens, unless they have a reputation for being excellent writers, are not good people to ask.
And I agree with @intparent 100%. The essay is a way for adcoms to get an idea of who you are as a person, beyond your stats. What should they know about your personality? They want to admit people they like.