Thanks for posting your query. It seems like you are in trouble and I am worried for you as well. Please do not be scared or think that you would be forced to go to a Rehab. You just need to speak to someone now.
My suggestion for you would be to find someone whom you are comfortable with and share your thoughts, may be a counselor or even a child psychiatrist
Self-harm suggests that there is an underlying psychological disorder in you. Refrain yourself from it.
Please do not wait longer, go ahead, consult a specialist, and please, at least attempt to tell your parents about it. I am sure they are the best people for you to rely on.
Hope this helps you. I would like to give you a more specific answer. You can ask me a query directly at this link.
Wish you good health.