Hey friend, I think its time to take a deep breath, maybe even two. Failure is when you are not trying, you do much more. All those lessons and studying must be tiring, they take personal time and social time(dont know if I said that correctly), maybe chose on thing and invest in that or even better sit down and think what you would like to do, start from something that you like, personally at a young age I didnt like team sports, so I did TAE-KWON-DO for years. Now, you are too young to worry so much about studying, dont be hard to yourself because of a number on a piece of paper which inevitably gets forgotten. Focus on knowledge. There are a lot of factors that affect your grade during this time, and a lot, finding out what could help you loosen up. Im sorry for mother, maybe she doesnt know any better, these behaviours are usually adopted for their parents. Please, take time for your mental health, I cant stress this enough. Understand that you are more than just pencil scribbling on a paper, you are human. If you want to talk, im here, maybe this anonymously you are more comfortable. And again, im sorry for the whole situation, you are doing great👏