Hi Mary,
31 out of 50 is a passing score. Peterson's are infamous for being somewhat more difficult than the real thing.
Did you study the Instantcert material for Counseling? If so, I'm sure you will do just fine. If not, you should probably do some research on the actual theories, theorists, and concepts rather than leaning ENTIRELY on your own experience (although that will come in handy too).
I assume that you HAVE studied Instantcert, but just wanted to make sure.
Try not to worry, 31 out of 50 (62%) is enough to get you a pass. Any additional last minute study you do tonight, will obviously only help your performance.
I plan on taking this exam next week, so any feedback you can provide after you take it tomorrow will be VERY MUCH appreciated.
Best of luck,
Snazzlefrag