Okay... be sure that your finishing tests quickly doesn't mean you aren't fully reading and responding--that used to be a problem with me reading so fast! There's some reason your scores are down...see if the counselor can help you discover how much the anxiety is hindering you.
Ah yes, the big "what if"!

Don't let your mind go there. Block those thoughts and counter them as they come into your mind. You ARE doing the best you can do, and you're trying to improve on top of that. What more CAN you do? Nothing! You are doing the best you can do...no one (not even God, if you believe in Him) can expect you to do more than you can do. Get it? Now breathe.