Depression

So I'm 13 the now and I have been depressed since about November 2016, so a year. I have nevee told anyone, I keep it to myself so this is hard for me to write this but I know I should let it out somehow, so I've never been professionally diagnosed but I self diagnosed myself in April 2017, when I started to self harm, my depression was really bad over the summer and I cut myself alot, during the past few months I havent cut as often and I feel like everynthing is looking up but I know that won't last long. People in my year self harm (Im in High school btw, I live in UK) There are boys in my class that make fun of depression and self harm, they even cut themselves together as a joke. I don't know why I wrote this but I felt like I should as it is anonymous and I can let it out i guess. So if anyone actually reads this, idk what I'm expecting in reply but if anyone out there is depressed and self harms, comment you're story? xxx