6-11
It sounds like you have some experience with the use of mental imagery, but may need some additional training in how to make your mental images controllable and vivid, use all of your senses in your mental imagery, and/or make sure that you can use it when you really need it. You may benefit from reviewing the below exercises.
Mental Imagery Exercise #1 - HERE
Mental Imagery Exercise #2 - HERE
Mental Imagery Exercise #3 - HERE
Mental Imagery Exercise #4 - HERE