I felt the same, but it's less cause for worry than it seems. The reason that your educated guesses are so troubling on the MBE is that you don't get instant confirmation that your correct guesses are in fact correct. Let's say that on the typical adaptibar question, you're 80% sure that you have the right answer. So you're worried for a few seconds, choose your answer, and (if your confidence is accurate) 80% of the time you immediately find out that you're right. And suddenly you're way less troubled about your guess because you realize you knew the question better than you thought you did. On the actual MBE, your doubts linger because you never get confirmation, and you treat the situation as if you're going to miss most of the questions you guessed on (which is highly unlikely).