Well, cutting / self-injurious behavior, is classified in the ICD-10 CM in part as:

"A disorder characterized by an enduring pattern of unstable self-image and mood together with volatile interpersonal relationships, self-damaging impulsivity, recurrent suicidal threats or gestures and/or self-mutilating behavior."Since you say the onset was 5 years old and changed dramatically at 12, I know it's likely unhelpful in this moment, but I'd strongly suggest you consider speaking with a mental health professional like a social worker, a professional counselor, a psychologist or a psychiatrist.

BPD is a personality disorder caused, it is theorized, by a host of things (mostly early childhood traumas). Currently the "Gold Standard" of treatment is called "Dialectical Behavioral Therapy" which involves teaching people coping skills for analyzing and controlling their symptoms.

Perhaps something that might help, though might hurt - you have to decide - in the now is to take a look at what's called "Behavioral Chain Analysis." A good description of it can be found here:by web surfing "dbtselfhelp behavior chain".

I'd give you the links but I don't have enough posts to allow me to.

Behavioral chain analysis involves looking at antecedent events, (what leads up to) the behavior, and what you do / feel after. Given that you feel "exhausted" in your mood icon, that might be a clue - I really couldn't say.

Be careful though - you don't want to have analyzing your behavior triggering your behavior. If the process of going through and thinking about your present incident, or past incidents, and looking for similarities in causal chains causes you distress then STOP until you can practice the process under appropriate supervision.

If you feel actively suicidal, please report to an emergency room immediately, and be careful - this cutting behavior, or other typically "borderline" behavior, can wind up being unintentionally fatal.

Theory says it's a "cry for attention" or for help. My best suggestion is that you take the opportunity to seek some as soon as possible.

Good luck.