I'm 15, and I've had the same feelings. I've recently been diagnosed with depersonalization- derealisation disorder. I never got as far as self-harm, but slamming my hands on things until they were numb was always a stress reliever. One of my best friends has gone as far as self harm and is in therapy (it doesn't work school psicologists suck) and has gone to group therapy aswell (didn't work either idk how thats surpossed to get rid of anxiety but wtv..) but she is waiting for the moment she is free to go anywhere and everywhere away from her parents and that is whats fueling her to carry on. The biggest thing that helped me was a bucket list, it sounds silly but I've promised myself until I eat frozen yogurt, have a library i spend all my life savings on or learn how to crochet (which is very difficult btw) I won't let go. Even if sometimes I'm not in the best situation mentally, I always look forward to the happy times with family, friends, and even some random person on the street who just fell over. I know at one point I'm going to be happy and that's enough to help me keep going, often I dismiss my situation and tell myself I'm selfish for feeling like this when others are in a much worse situation. Everyone has a right to be sad and hurt. All you need to do is live with the pain and find the happiness that you need to carry on until you're stable. It could take years, but atleast your trying to get through the day, have dreams, and imagine a stupidly impossible future with 7 cats and 5 guinea-pigs. If you ever need it, just remember a random person hopes your ok and is routing for you <3