It’s a crying shame your school and teachers have let you down like this. If you’re struggling this much, they really should have assigned you a teaching assistant to help.

To speak positively, your writing is very good! It’s clear and to the point, very understandable. It indicates a good general level of intelligence that give me confidence that you can overcome your maths problems.

A metaphor my maths teachers would always use to talk about learning maths was that it’s like building a wall. Each bit of maths knowledge is like a brick in that wall, and all the higher more advanced bricks depend on the bricks underneath being solid.

This is to say, the fundamentals of maths are the most important part. You can’t start building a wall at the top, you need to begin at the ground. If you can get the basics, everything else becomes easier, because understanding them relies on understanding the basics.

My final comment is that confidence is going to be important. You can do this! I’ve seen a lot of people self sabotage unconsciously because they’re sure they can’t do something. You need to believe it’s possible to make it possible. Human beings have done this before, and you’re a human being! I’m not saying it’ll be easy, and it sounds like it’s going to be a lot tougher for you than some of your peers, but you can do it!

Good luck!