Disclaimer: nobody will be able to predict how you'll do on the actual exam, this is just an opinion.
Your scores are good, generally most people recommend that you score 80-85% on the Prepcast exams. I wouldn't place too much emphasis on your performance on the PMI practice exam, I did it as well and found the questions to be more similar to the Prepcast style, but make sure you understand why you got the questions wrong. Keep practicing your weak areas, I believe you're on the right track and that provided you keep your scores up you'll be ready for Dec. 15th.