First of all, and I know you know this, self-harming makes everything worse. It will make you more stressed, more anxious, and makes your stutter worse long-term because of those things. I'm not a therapist and cannot give you proper mental health advice, but I can tell you that being 14 means you're hardly a seventh of the way through your life. Getting through a stutter is a long, long journey. We learn how to deal with it, not cure it. I hope you can find more detailed advice throughout this subreddit about specific problems you might have, and definitely post about them too. We'll give you our best advice, but you're the only one that can make your stutter easier. It's an internal fight, so we all want to help each other.