Hey Bangbang,
Welcome to SR. Cutting is a problem that effects many teenagers today. People do it for different reasons, but the reasons usually revolve around escaping/embracing feelings. Some people cut to get away (a type of disassociating from 'real life'), others do it to feel something becuase they feel numb to the world. It is one way for people to cope with problems they are having.
We have some active discussions on cutting over at sober-teens.com (
http://www.sober-teens.com/forums/forumdisplay.php?f=35) that you should check out. Take some time to read through the links, I think you'll find that there are others who are going through similar situations, and maybe something they said will 'click'.
If you have any questions, etc feel free to drop me a line. (I'm the moderator of this forum and also the Impulse Control Forum where the links are at ST)
*edit*
Here is a thread about cutting that has some good info:
HERE (cutting...)
-pedagogue