Hi Martin,
I am in the same boat as with in regards to how much time I can devote to studying due to work. My exam is scheduled for the 29th this month and I started studying at the end of January, doing 1-2 hours a day during the week and 2-5 hours on the weekend.
Doing that 1st practice exam can be overwhelming if you've gone straight into it from the learning videos. I took some time and practiced getting used to the "exam environment" and questions style by doing sets of 25-50 questions under the Timed/Learning Quizzes. This really helped me focus on learning how to read a question and what techniques I should try to find the right answer. I did about 10 of these sets of quizzes and reviewed each one in detail, writing down why a certain answer was correct. If I still needed clarification or found I was continuously missing questions in a certain area, I would then reference the PMBOK section and take any notes I needed. I learn and retain information best by hand-on experience so I've also added to the PM PrepCast exam simulator with another online PMI certified exam simulator. I'll do a full exam one day on one site and then switch and do a full exam the next day on the other one. This is what works best for me, but for you it might be flashcards, reading the PMBOK, or re-watching some videos.
Try not to get too discouraged with your first exam score, see the score as an opportunity to improve. You have plenty of time before your exam to bring that score up. Keep practicing and studying and you will only get better!
Good Luck and Best Regards,
Leah Goff