Miss Manic
I was fourteen a long time ago and I raised two daughters who are now older than you. If either of them had told me what you are saying here, I would have taken them to a doctor right away. Why won't your parents be open to listening to you and your needs?
When I was fourteen, I was a suicidal mess but nobody noticed. If I self injured, and my mother noticed the wound, all she'd do is threaten to "tell my father". Fat lot of good that did; it made me hide everything I felt cause I didn't want to get into trouble. I finally was able to speak to my primary doctor when I went for a physical. He got the ball rolling and like it or not, my parents had to agree to my seeing a psychiatrist.
I don't know your life , only what you told us here. You sound like it's very painful living like you do. Whatever is causing you to feel this bad deserves to be investigated. I really hope you can find a way to do that.