Your letter shows me that you are a person who feels things deeply. Ironically, it is often the teens who are the most sensitive who do self-harm. The problem isn’t that you are ugly or worthless or stupid. The problem is a combination of holding yourself to impossible standards and not having the tools you need to cope with your big feelings.
Since you are a sensitive person, you will always respond emotionally to things. There is no way to make the world behave so that you won’t have things to feel strongly about. But what you can do is learn better and stronger coping skills. That’s where therapy comes in. But as you discovered, a therapist can’t help you if you don’t give the therapist enough information to go on.
I know it can be embarrassing at first to show a therapist what is really going on inside. But, trust me, therapists handle that sharing without judgment. We therapists want to help, not judge. I think you should go back to the therapist who began to get to know you. If you think you’ll have trouble talking about the self-harming behavior, take your letter and this response with you and let him read it. That will help you open up the subject a little more easily.
I really don’t think you want to die. I think you understandably want to feel things without being overwhelmed by the feelings. Please contact your therapist. You owe it to yourself to learn ways to handle your sensitivities.
I wish you well.