New and after some support

So about a year ago I graduated with my BSN and unfortunately I've taken the NCLEX twice so far and still haven't passed. I have terrible test anxiety to a point where I go completely blank during the test. I'm scheduled to take my 3rd exam in about a week. I feel like I'm panicking and maybe I should push it back a bit to give myself even more study time. I feel like I don't know the content well enough...but will I ever really know the content well enough? I've taken the KAPLAN course and I've been doing 50 Q's a day since May. Most of my score's range anywhere from 50%- 75%. Has anyone taken the Kaplan course? Did you wait to take the NCLEX until your scores were well above 60% (the passing rate I believe)? Any tips or advice would help! Thank you :)