Are you seeing a therapist? They can sometimes help you with other coping mechanisms. Self-injury is generally just that - a coping mechanism. To stop you generally need to build up other ways to manage the stress and find release.

If you haven't already I would suggest you have a look through the thread Things to do instead of hurting yourself which is stuck at the top of the SI forum. It has a lot of tips and tricks that have helped others when trying to overcome SI.