To tell the truth, online is not a place suitable for studying with peace of mind. It can only help your study. If you want to teach yourself high school mathematics, you should borrow some textbooks first (Xinhua Bookstore can buy or go to a waste recycling station or an old bookstore near high school). Don't do mock college entrance examination questions as soon as you come up, you can't do it! After reading the textbook, I will get 1~2 college entrance examination review materials. For mathematics, I recommend using the college entrance examination to review lectures and get some gold papers and little red books to do. The exam survey is also good. Our school used to use these kinds, the quality is ok, 7~9 yuan one, the price is good.
It takes 1~2 years to get results, during which you will be hit endlessly, just like every high school student, but it will pass. If you find some training classes or people with connections, you can go directly to repeat classes, which is better.
Finally, I wish you success! Come on!