And I'm so worried I won't pass, or something will go wrong, or something.

Hope everything goes fine! Let us know how you did!

it's okay, clam down and think that everything will be fine and stop cursing yourself.

Take deep breaths, you can do it. Try not to work yourself about it now, you've done all the practise and hard work, and can't do anymore. Show the examiner how well you can play.