One: the foundation is not firm, and the ground shakes. Mathematics is inherently difficult. You haven't studied mathematics seriously for a long time. It is estimated that it is difficult for you to settle down and study mathematics, but you are eager to learn mathematics well. I think we should start with the basics. You can take junior high school math books first and review the basic knowledge, such as linear function and quadratic function, which are used more in senior high school. The other is the cultivation of mathematical thinking, which really has nothing to do with high school.
Two: because the foundation is poor, the foundation is thin. It is estimated that it is difficult to keep up with the teacher in class. I suggest you find a one-on-one tutor or remedial class. Just let him teach you the most basic things, such as sets, complex numbers, simple solid geometry, simple series and some simple function problems. Simple knowledge tests add up to 50 or 60 points, which is not very difficult.
Three: You have to overcome psychological barriers. The more you are afraid of him, the more uncomfortable you are, and the more disgusted you are when you see him. So, you should adapt yourself to him slowly and do a few simple papers every day. Generally speaking, a college entrance examination paper, the first five multiple-choice questions, the first two fill-in-the-blank questions and the first two big questions, including the first question, are not too difficult.
Don't be afraid of poor foundation, you can't eat a fat man, since you can realize your own shortcomings. Then there is still more than a year, and it is not a problem to get a 90% in the study, as long as you can work hard and be practical.
Finally, if you don't understand, you can ask again. I hope you can adopt my answer. Thank you. Come on, it's not too late to work hard. It took me a year. In my third year of high school, I got an English test from 70 to 130. Anything is possible.