Third world country high school sophomore seeking advice on getting into good unis.

I've got just about every problem. Guess I best start solving them one at a time.

Hey.
First of all, I intend to make this post longer than most forum posts for two reasons. Obviously, there's a lot that needs to be said. And also, I am trying to avoid quick answers. By making this long, I will filter out the 'you're doing good dude' type of people.

I'm 15 years old, male, from Croatia. I suffer from depression, suicidal thoughts, disagreeing with just about everyone in everything, obesity, but what I'll focus on now are my academic problems. To give you some context, Croatia has got a type of a high school system in which there are multiple tiers of high schools. They differ mainly by how long the courses are. The 3-year ones are almost all crafts, exempli gratia salesman, florist, barber, driver et cetera. You can't pursue higher education with these. The 4-year ones can be divided into the 1) gymnasiums and 2) 'finer' crafts.

1) Gymnasiums. They are the top tier high schools. They offer the most prestige courses where one doesn't learn an actual profession, but general subjects like in Western schools. Note that they're not related to Physical Education any more than other schools, I don't know why they're called as they are.

2) 'Finer' craft schools. These offer courses like 'physician, economist, commercialist, technical drawer et cetera. These are easier than gymnasiums, and you can pursue higher education with them. None of these crafts (neither do 3-year crafts) actually prepare you for what they're meant to be for. Perhaps back in Yugoslavia you would find a job related to your high school, since the country was lacking college graduates, but this isn't the case anymore. You do learn about what you enlisted in, but the subjects are useless. Having graduated from a finer craft school without college equals to having just a 3-year school.

And now, it's time for me. Neither of my parents has college. They're a bus driver and a kindergarten cleaner. They never pressured me to get good grades. They always cut me slack in everything, and let me live my life how I wanted to live it. I was one of the best students in elementary school, when all that mattered was intelligence and you learned most if not all in classes. But as time went on, you had to study more and more. And I failed at this. Every kid finds it boring to study, especially when they're thinking a few months ahead tops, not years ahead like I am now. With zero motivation from my parents, I naturally did not excel at my last two grades - the 8th grade of elementary, and 1st of high school. I was under average.

Now, I'm starting to read blogs about successful young people living in Western countries with terrific jobs and careers. They all get paid a lot, and live a happy life full of recognition and prestige. This is why I want to, with all my heart, live the same life they're living. I want to go to a good university and do something with my life. Oh, boy do I wish I felt the same way two years ago when I had to choose my high school. My parents wanted me to to enroll into an even worse course than my current one, and I hadn't even thought one bit about gymnasiums. I didn't even want to go to college back then. The cancer that is this whole life surrounding me was getting to me. But I broke free, I untied my hands and ventured into the life of Western people. Sadly, too late.

My course is economist and I'm a sophomore. It's better than around 70% of other courses, being topped by gymnasiums and other good 4-year finer crafts. It's relatively easy, and it's close to one of the courses I'd potentially like to study: economic psychology (also known as behavioral economics). My grades are average at best. Croatia has a grade system ranging from 1 (F) to 5 (A). I finished last year with 3.40 (C+). Even if I got good grades in my last year (4.70 or above I reckon would do the trick), I'm afraid no admissions board will accept a student from a non-top-tier high school. Because they'll think that exempli gratia 4.80 equals 4.00 in a gymnasium. I have the following questions for the few of you that read this to the end. Thank you for it.

Presuming I fix my grades to say 4.80 (quick reminder, 5.00 is max) in my senior year, is there any chance an admissions board could be fooled and let me enroll in economic psychology?

Do only senior year grades matter to admission boards, or grades from all years, and to what degree?

To wrap this up, I'd like to say that the reason of bad results in my last year was solely general laziness which was caused by a severe lack of motivation and lack of regard for academic success. The toxic words of the two devils I'm unlucky to call parents still ring in my head: "Come home with a 2 (D) and we'll be happy". I'm very smart. And if I'd been born to a better surrounding and to better parents, perhaps now I wouldn't be checking if I could get into a university: I would be checking I could enroll into Oxbridge.

I'm hoping to find help which I'm desperate for here. Thank you all for reading and for helping me.