Hi, I understand the distress caused to you by your problem. You seem to be suffering from Pica. Pica can be a result of nutritional deficiency like iron deficiency anemia, zinc deficiency, etc., or can occur as part of impulse control disorder. Eating slate pencils is definitely not healthy and can cause gastrointestinal problem later on. So, i would advice you go ahead and meet a psychiatrist as soon as problem. if nutritional course is ruled out, you will need to be treated by drugs like selective serotonin reuptake inhibitors or behavior therapy (habit reversal therapy specifically). Behavior therapy generally offers better results than drugs per say. Wish you all the best.