How should i change my approach on practice tests

Hi i am currently a junior in high school and struggling to raise my score here is an overview:
10th grade PSAT i scored a terrible 137 with zero prep back then i did not know what the psat was and all (it had only been 1 year since i came to America)
i then kind of put it to the side until around September junior year i understood what the psat,act and sat were . i started panicking and googled stuff about sat and all and two days before junior year psat i watched all of kaplans psat cram sessions . i made a 142 not any improvement from 10th grade. i logged onto collegeboard looked at why i missed my psat questions. I then signed up for the march sat in december and took sections of cr and math in which made around high 40s on my psat (i know its bad). i used the blue book and scored high 500s and low 600s in both. in january and feburary i took full length practice tests from the back of the book and scored 1700s and 1800s now i have around four days left for my march SAT and i know i will get around 1700 and 1800s but my aim is atleast 2100 for the next time i take it. Its like my score is just hovering around the 17-1800s i cannot improve . I would be grateful for any tips . Thanks