A grade is a weather report on one test, not a forecast for your whole life.

One score describes one morning: how you slept, what came up, which questions happened to land on the page. It is real information about that morning and almost none about what you are capable of, even though it rarely feels that way while you are holding it. Treating a single number as a summary of a person gives it a job it was never built for.

Look at the pattern across several results rather than the worst one. Ask what the mistakes have in common, because that part you can use.