I'm glad you did not change your mind and delete anything, what you say will be familiar to many people, myself included, and shows you are living a life no one should have to. As to the other people in the world, you are as welcome and entitled to be here on the Forum as much as anyone else.
You are also completely anonymous here, that's good. The Forum takes great pains to keep you anonymous, that's how it should be. I guess if not nobody would say anything
Being always tired, feeling worthless, useless, that everything is pointless; sounds an awful lot like I felt when starting to become ill with depression. I'm no doctor and can only say your thoughts and the way you write rings a strong bell, it sounds familiar.
Trying to keep living this way is something I did, it was in fact a pretty big mistake, I left things for too long, and became much harder to treat. In the meantime life got worse. No way I could 'fix' myself.
I do not know your age or circumstances. If at school then perhaps talking things over frankly with a parents or school councilor might be a good way to go. For older persons a long appointment with a GP and talking about your life and feelings, holding nothing back (which is hard).
Then see what happens. You might be found to have depression or some similar illness and require treatment, nothing to be apprehensive about. .
It all starts by being assessed by a medical professional, not something to be hesitant about, they are there for you.
If you are under 25 then I'd suggest using the Kids Health Line which has phone, email and chatas well
They have a great deal of experiencing with situations liker yours and you can talk to them more than once without re-explaining things.
Apart from medical support, is there anyone in your family who you can go to and will take you seriously and listen caringly? Maybe even take you to the doctor themselves? Do you get on with your mum?
You have done an excellent job in saying more than enough to start with, and I appreciate that it would not have been an easy thing to do
I hope to hear from you again