I have seen lots of positive qualities in you from reading your posts.
You are extremely articulate and intelligent. Your spelling and grammar are exceptional. You are also careful, conscientious, kind, sensitive, thoughtful and compassionate.
You could see if you could find a job in an office. You can obviously communicate well using a computer, so you might enjoy an office job -- working on your own tasks, typing, doing data entry, etc. When you're 17, it's not important to worry about what sort of job you're going to have for the rest of your life. It's just good to get some work experience.
I'm a communications coordinator now -- writing, art directing, etc. and before that I was a graphic designer for many years. So, I'm in my chosen profession. Before I got to my chosen profession, though, I worked as a temporary secretary and then a legal secretary. I knew how to type and I was articulate, so I did well in those jobs and gained some positive experience, as well as earning money to pay my university fees. Doing well at a job can really boost your confidence too. You have lots of positive qualities. I would hire you if you lived nearby!
Perhaps you could also consider if you would enjoy working in a hospital or nursing home -- helping to care for people. You seem like a very caring person, so maybe you would enjoy doing something like that... or working at an animal shelter or veterinarian's office... lots of possibilities out there besides being a shop assistant. I worked in shops a few times but really didn't enjoy it because I'm not much of a sales person. I always preferred to leave them alone to their shopping and it turned out that's not what my bosses wanted.