If you learned a lot, and it's not only a significant amount but a significant part of your life as well, then go for it. Colleges want to see that you're grown up and can handle things, and they want to see how you grew up and learned to handle things. Progress is good! If you have any other experiences that you're considering, just think about if they're striking, if they've affected YOU a lot, if they are experiences that everyone else has, if your reaction or lesson from this experience is typical or unique, etc.
Admission officers read a lot of essays, but most people BS them, or make them elaborate and fluffed up just to impress, or completely make them up, so if you have a meaningful essay, it will be noticed. Make sure your essay is written genuinely, and has a very sincere voice- it doesn't hurt to be humble, either. Not suck-up humble, but don't be arrogant or too conceited, because you are basically begging these people to let you into their school, and this essay is part of the offer you're making.
As far as the essay after it's written, give it to a ton of people to edit. Not only counselors, teachers, and tutors, but your classmates and former upperclassmen who have finished the process. I wouldn't really suggest having your parents look at anything but the final draft- let them know that you're working on it and not slacking off, but they're probably not going to be able to read it subjectively, and will either over praise you or overly criticize you. Your counselors, teachers, and tutors will be able to read it from the officer's point of view, but they may make editing suggestions that will change the entire point or feel of your essay. Your friends, however, KNOW you- they will be able to point out, "this doesn't sound like you", "you usually write with a lot of vivid description, let yourself loose here so it'll be more interesting", "I remember that, didn't this happen also?", and so on. Hunt down friends who are good at English too!
But remember, this is YOUR essay, so don't feel pressured to take any edits that will make it otherwise. Always take edits that are purely grammar though

You don't want grammar mistakes!
Good luck~