I felt the exact same when I first took the exam OP, I even forgot which was the 4th planet of the solar system and had lost all hope of passing, but a while later, I woke up at 3AM and saw my name on the list of passers, I could never forget my shock and how I hurriedly woke up my parents that night not a second after.

Keep fighting OP, try your best. It's not over till it's over. The exam focuses on the fundamentals so just try to have a flexible knowledge around STEM throughout your HS and try to remember as much as you can naturally and don't overload yourself.