I know how you feel, when i was unwell the voice used to tell me to kill myself so i would self harm as a compromise. i never did it to die but there is always a chance with self harm that it could go too far.
If you learn how to do this, you won't need to self harm (suicide also being a form of self harming).
You're not expressing your feelings so they're coming out other ways. Start using your words to express yourself. Speak up when you need to. Don't bottle things up. It doesn't work.