Firstly, you really really don't 'deserve' it. Nobody 'deserves' pain. I know you said it relaxes you, just think how guilty you'd feel afterwards. It's not worth the few minutes of relief it may give you. And besides, you've gone over a year. That's fantastic!
Like Cara said, try wearing gloves at night so you don't scratch yourself in your sleep, and try seeing a doctor about your panic attacks.
Finally, have you seen
TH's list of alternatives to
SH?
http://www.teenhelp.org/forums/f12-s...ves-self-harm/
Try some of those out if your urges get too strong.
Don't give in lovely, you're so much better than that! You can beat everything <3