hi everyone

hi, im 17 and ive been picking at my skin, mainly my arms and face, since i was about 11. i cant remember why i ever started, or why its become such a habbit, its always bothered me, the scarring and going out in public. im always so envious of those with perfect skin, i would have had alright skin if i never had.ve touched it. i really wanted to stop, ive tried cutting my nails too short, wearing gloves, long sleeves, but that nervous urge just gets to great. ive thought through over and over what could be triggering it, and how i could stop it. i suppose ive always had low self esteem, and a bit ashamed of myself. like when i was younger i had horrible nightmares, was scared of the dark and wet the bed until i was about 9 yrs old. i never really assumed that would actually cause skin picking, always thought it would be some kind of severe loss or trauma that would do it. although my older sister by two years, began to develop a drinking problem when she was about 14. kicked out of home for her drinking habbits when she was 16, rehab when she was 17, now about to turn 19 and is living on the streets doing hard drugs and stealing (court three times and put in jail for a week). but the problem was, although she wasn't professionally assessed (my sister refused it) my of the social workers etc. believed she had a form of autism or borderline personality disorder. me and my sister were very close, and still are although i dont see her much. im not troubled by any of it however, so im worried there may be a cause to my skin picking other than environmental causes. a link between my sisters possible mental illness and my compulsive self mutilation? (i have other bad habbits other than skin picking, but its the most damaging in matter of self esteem) any clue would be greatly helpful thanks sarah