I’ve gone through so many challenges in high school with my OCD, depression, anxiety, moving schools 3 times and the loss of my mother. How can I convey this in my college essay without appearing overly sympathetic due to my high school experiences?

I’m sorry that you’ve had to deal with so much at such a young age.

If I were you, I would write an essay that focused on resiliency and the ability to overcome trying situations. That would allow you to describe your situation while not seeming like you are asking for sympathy or special consideration. Good luck.