quinze....check the syllabus to see that you have been passed on all the pre solo requirements.
Go and talk directly to the CFI. I'm interested in the fact you havent done engine failures yet. When you are asked to learn things before lessons , make a point of getting on top of memory items and actively demonstrating your knowledge.
You should get a recommendation regarding the best instructor for you, and stick with that instructor.
Make a point of getting an effective debrief after each flight, and habbitually debrief yourself.
I was 17 hours to solo, and I knew I could have gone earlier, but the young instructor at the time was new at it, and was just being carefull.
Make sure its not attitudinal, but I doubt that. What is your age may I ask?