You filed correctly. Great job!
F1 visa holders are generally exempt for any part of five calendar years, meaning you will not file as a resident alien until your sixth year in the United States. Assuming you spent more than 183 days in the U.S. in 2020 (satisfying the substantial presence test), then your residency began on January 1, 2020.
See Example 1 in Alien Residency Examples.
