A long text about career

What do you think? Would it be a good presentation? Are there any grammar mistakes or any mistakes? I'm actually still new to writing what is more I am not a native speaker.

As far as I know, you plan something, you would like something, but nobody knows what the future brings for you. Admittedly, it is really good to know what you want, but always be a little flexible and have a plane b, c or even more. I am not just saying but I have experienced it as well and I don’t want make the same mistake after high school.
So the previous year I needed a plan b. And why? Because, I made a mistake, I almost ruined my whole future when I was choosing a grammar school, but I am grateful since everything turned out well at the end.
Originally, I went to Budapest, to a secondary school called Szent László Grammar School and I learnt telecommunication. But soon I changed my mind since it wasn’t for me, I didn’t like it and it was a really great burden because of the distance and the inappropriate students’ hostel. As a result of that I decided to come back and learn hear. It happened to be a good plan b since fortunately, everything went quite well.
In spite of this, I was a bit desperate, because I didn’t have a goal anymore. I needed a new plan for my future. And this is when things got exciting. No actually, it didn’t. You know, if you don’t know what you want, you are not able work as hard. And remember when I said I had been grateful, I mean I still am since I came to a language preparatory class, to Lehel Vezér Grammar School and it kept my interests. I fell love with English for my whole life. But, you may ask why I am telling you this anyway since it’s not my question that I’ve got to answer.
Well, it is not true. Maybe, partly it is. I could list what I want now. I could tell you that I want to have a nice environment with an understanding, fair but demanding boss. What is more, I could also tell you that I want a high salary and do a white collar work.
But, it would be too obvious and what I really want is to tell you a story that is still forming since I wouldn’t really be able to answer these questions with knowing that my answer can change really fast, because my personality is still evolving.
So, English didn’t actually made everything good, but it was a good starting point.
And in the recent past I was dealing with those tests which theoretically help you to choose a career. Finally, during a test like these I realised that a medical career would have been totally suitable for me. I love science especially chemistry and biology. But it was still too broad, because there are all kinds of medical professions from general practitioner to surgeons. And well, somewhere in between them I got a result. Sports physician. Yep, I don’t even know why I hadn’t thought about it before. I mean, I hadn’t considered it like an opportunity at all. But, it seems obvious now. However, there are some problems as I have mentioned. I may change my mind in the future again or might not even be able to go on to university. Who knows, I can just hope that this profession is really meant for me and of course I do my best.
So purely, I would like to be a sports physician, but I try to remain a little flexible as well.