I have a history of self-harming, mainly by cutting and burning, but also by scratching, biting, head-banging and self-hitting, among other things.
I do it when I feel more depressed than usual, when i'm anxious, when I feel like i've done something wrong, when unexpected things happen, if I speak too much or feel like i've imposed myself on others, when people have been shouting, when i've been bullied, picked on or had an argument, when I have sensory overload, and when i'm having negative thoughts about myself, or thoughts about hurting or killing myself.
I do it to punish myself, to comfort myself, to make the outside of my body match what goes on inside my head, to release stress and bad feelings, to have control over something, to see, taste and smell the blood, to make myself feel, to try to make myself seem real, to get through the day and keep on living.
I'm sorry to hear that you have felt the need to self-harm, please just remember that you are not alone.