Sorry to hear what you've been through. Firstly, well done for having the courage to admit that this is a problem. That's the first step to recovering from an issue or problem, so you're already on your way!
From the first 11 years of your life, you had a very normal life. The stand out fact was social isolation. Being located away from peers, struggling to make friends and consequent loneliness. You said that it wasn't so bad, but I'd imagine that it probably affected you a lot more than you might think. Bullying may have also contributed to this - wearing away confidence and esteem may have caused you to be increasingly hesitant when it came to social interaction, and much more conscious about what others thought of you. The fact that you described yourself as weird as a child when you had quite a normal first 11 years points this out.
The hurt of social isolation is what I suspect led to the instances of cat-fishing (pretending to be someone else online). The bullying would have dented your confidence, such that perhaps you didn't feel that you were good enough to make friends. Thus, you turned to fake profiles in order to be someone who you thought was better, and thus would have a better chance of interacting with others. This became something that you desperately wanted - perhaps a mixture of being denied the opportunity for a while, as well as missing the social interaction that makes us human. The addiction formed, and intruded on other parts of your life - academic success plunged, mental well-being plummeted - and the decline of these areas would have only made that addiction stronger, since you would become more desperate to hang onto that source of happiness. After recovering from those events, you became lonely again, and so the cycle repeated. "En" happened, and you lived your social life as another person. And then you get the message that academic performance is poor, and then the depression came back.
Amidst the confusion, there are several clear takeaways from this experience:
1) Your desire for social interaction is very evident. You clearly want to engage in interacting with other people, but have kept resorting to a medium that doesn't make you happy. In that case, you need to take that first step, and start talking to people. Maybe you practice small-talk, or perhaps you reconnect with friends. Whatever it is, you'll only get better at social interaction through practice, so the more you interact with others, the better you'll get in time! Of course, it's much more comfortable behind a screen, but you need to go outside your comfort zone here. When you next see that person in a shop you regularly visit, talk to them! Or if a neighbour is passing by, say hello! Make that first step, and get yourself out there!
2) You know what you want to do. You know you want to become a teacher, and you know that you are very good at programming. Perhaps then, you could combine the two - becoming a programming teacher at a college or high school. However, you need to work backwards from that. If you want to be a teacher, you need the qualifications. If you want the qualifications, you need to pass those exams. To pass those exams, you have to study and work hard. To work hard and study, you have to improve your mental well-being and take back control of your life. It's never too late to learn for a qualification. You still have time on your side, so keep studying for those qualifications you want. Work on these one step at a time, and you'll be on the road to success
3) Online interaction isn't helping you right now. While it is bringing you instant happiness, it staves off face-to-face interaction, which only stalls your social skill improvement that you clearly want! It has ended you up in problems before, and addiction has also happened. I would stay away from it, since it is negatively affecting other parts of your life. Cut it out, redirect your energy into other parts of your life, and maybe later you can come back to it. However, you have to be disciplined, and take the steps you need to recover - if that means cutting off online interaction completely, then that's what must be done. You may be unhappy now, but you'll be much happier in the long run.
4) You're on the road to recovery. Whether you realise it or not, you've already taken big steps to recovery. You've accepted that there is a problem. You've shared your experience online. You've accepted that you need to get help, and have done so with the counsellor. Work with the counsellor in order to put you back on the right track, and live a happier life. You've already been brave by sharing and accepting this problem, so keep showing that passion to fight this battle and win this war! I believe in you!
I'd love to chat with you sometime! Hope you feel better soonx
Much love <3