Is this categorized as self mutilation?

whenever i get mad, stressed out, or frustrated i tend to let out my spurts of anger by scratching my arm, sometimes its just a scrape mark.. like a scraped it on wood or something and it pulled up a little skin. you know what it looks like.even more than making a scrape, my arm will bleed. dripping blood. as it drips i just look at it like. wow, i just did that. i cry sometimes when people see the scars on my arm. its my only comfort zone. my coping skill. its a place besides my brick wall i put up around myself that keeps everything in and everyone out. thats how i like it. im very much overweight. im 13 and 152 pounds i want to lose weight before school starts again. so tell me do i self mutilate. i eat out of self boredom. i eat , i get laughed at, i scratch, i cry, i eat, and it starts over again. do i self mutilate and do i have an eating disorder?