Glad to hear that you have your DS home, i used to run away from my mum when i was a teengaer - i really was just a case of being a bit of a 'rebel' and also it didnt help who i was hanging around either.. NOTHING my mum said or did made me want to stay home... i know this isnt much help but i think its just a phase some of us go through unfortunatly for you it hasnt come at the best time.
i found the more my mum tried to disipline (sp?) me the more i would be naughty.. im not saying to let him do whatever he wants, let him do things to an extent like yes u can go do such and such but please be home by ?? time.
i dont know if that helps much but just giving you a point of view coz i was that young not so long ago