Have you heard of the Sylvia Plath Effect? Apparently, female creative writers are more prone to depression and suicide than others.
I used to write angst and violence. It was after a very dramatic and traumatic part of my life. When I read my novel a couple of years later, I realized that I mirrored some real-life issues and people into my story. In a way, I think writing about disturbing things is a coping mechanism to get through real life. It's therapeutic, so just keep going.
I high advise you to keep the more shocking stories away from your school, though. Your teacher might think you have emotional and mental issues and report you to the guidance counselor.
Not all those who wander are lost.