Perfectionism in itself isn’t a negative thing. Healthy perfectionists set goals for themselves and work hard to achieve them. They aren’t satisfied with average work. They want to really do their best to get whatever it is as “perfect” as possible. The important words here are “as possible.” It’s impossible to be really perfect and healthy perfectionists know that. They don’t become depressed when their best efforts fall short.
Unhealthy perfectionists, on the other hand, set unrealistic goals and feel terrible when they can’t meet them. They get little pleasure from their successes, always finding yet another thing that needs to be done before something is “perfect.” Falling short of perfect often makes them fall into a depression.
From your description, it seems that you have developed an obsessive-compulsive disorder that centers on an unhealthy idea of perfectionism. It has become so intense that it is interfering with your life.
I’m afraid a few exercises and even time machines aren’t going to fix this. You need the support and consistent practical help that a mental health counselor can offer you. I urge you to talk to your doctor or school counselor and ask for a referral to a therapist who works well with adolescents and with forms of obsessive-compulsive disorder. Some medication may also be suggested to take some of the distress down a notch so that you can do the work you need to do to change how you think. Please do see a counselor for an evaluation and for suggestions about how to approach this problem.
I’m very glad you wrote. You’ve suffered with this far too long already. The good news is that you are only 16. If you work on the problem now, you can live a life free from the stress and anxiety that currently is ruining your life.
I wish you well.