Score raise?

Hey! So I’m in a tight spot. I just took the SAT’s and I got a 1720. It was a complete shocker to my 2020 score I got on my practice test. On the test I got a 600 on critical reading, 620 in math and a 520 on Writing. I feel like I really bombed my essay. I really want to raise my score. I sort of crammed during this test I feel, maybe two to three weeks of test prep, and I was real nervous in the center. All advice will be appreciated. YouTube videos I can watch once a day, a list of vocab I can memorize. Also, would it be wise to teach myself prefixes and suffixes? These were things I was never taught in school. Another thing, if I wanted to raise my score significantly, like a goal point of 2100’s when should I take the test and approx. how long should I study? I’m a junior so studying in the summer would defiantly be a option, however, I wanted to test a early decision for two schools. ugh. help!