its kinda scary how your whole life depends on how well you do as a teenager
It doesn’t! Your whole life does not depend on how well you do as a teenager! I felt that way too but nothing I did as a teenager affects the way I live now nor will it affect the rest of my life.
The only way that teenage acts affect the rest of your life is if you do something like get pregnant or get someone pregnant. Or get arrested. Things that would affect your life if you do them as an adult too.
Don’t think that school choices decide the rest of your life because they don’t!