EM07,
Have you taken any of the PM Prepcast Exam Simulators? You mentioned taking quizzes, but I'd strongly encourage you to go through full length exams from PM Prepcast. If you've done them, and you're scoring in your 70s then you should be ready. The PMI Study Hall is a nice bonus to familiarize yourself with the vagueness, but I would not use the score from the SH to assess whether I'm ready or not for the PMP exam. From experience, I can tell you I did very poorly in the SH exam simulator (around 64%), but since I did well in the Prepcast Exam Simulators, I felt confident going into the exam. Since you mentioned you fear failure, I will say that you probably will never feel like you are ready to take the exam. I would say go for it, you don't need to be perfect. Wish you all the best, you can do this!
Regards,