I don't know what to do!

Try UWorld. Cheap but good.

If you have done self-study three times and failed after each prep, it's time to do something different. Find a tutor who can do 1:1 study prep with you, and let that person figure out where you might be coming up short. Contact your nursing school, ask if they have a tutoring program; many schools will be able to provide a list of names of people who may be available to tutor you.

You cannot do the same thing and expect a different result; perhaps it is the prep material, but a far more likely explanation is the way you are going about choosing your answers. People pass and fail with ALL methods; you need to sit down with someone who can (hopefully) help you pinpoint where you are going wrong, why, and what to do to fix it.

Good luck!