[sebg]

You could also try beast academy and aops. We are huge huge huge (did I mention huge?) huge fans of them and have worked through pretty much all of their classes (1st grade through pre-calculus thus far).

Beast academy is around 15/20 a month and apps is more but you can just buy the book and work through it. Richard (the aops co/founder) has a ton of YouTube videos as well.

A third option is aops’s alcumus - which is a free math problem database. We use that a bunch as well and you could use it to figure out what you know and don’t know