Hi Bonnie,
Take a deep breath, we've all been there
I would suggest you not think too much about how to detect difficult questions, how to keep a track of them, and worry about your scores based on whether a question seems simple or difficult. Rest assured, as the passing score of PMP Exam is now based on “psychometric analysis”, candidates would get a higher score if they can answer the harder questions correctly and a lower score for the easier questions. This means that the harder questions are worth more than the easier questions. So, the minimum number of correct answers needed to pass the PMP Exam is determined by the overall difficultly of the exam. Therefore, when preparing for your PMP Exam, do not just rely on a single provider of PMP practice exams / exam simulator, as one might be unnecessarily way more difficult than the actual exam. It is more advisable to try questions from different providers in order to understand your strengths and weaknesses. Just focus on giving your best while answering a questions, the exam simulator will automatically adjust it's passing mark.