I wouldn't put too much weight on comparing how many practice questions you are answering right or not. I felt like I missed a lot of practice questions, but learned a lot from the review book.
91% of people taking the FNP ANCC pass.
You might want to see my other thread "I passed ANCC FNP exam"
I listed some tips that i thought might be helpful.
you have 4 hours, you can review questions, I took ~3 hrs answered all questions and had time to review.
neelia