You sound like you almost have everything needed, but I would recommend you get a care plan book. Amazon has several. They tell you what interventions you can do for EVERY nursing diagnosis, they are very helpful. Good luck and trust me do not say the word nursing the entire summer because when you start school you will get tired of hearing it!
In our class we have had a couple of people fail their competency tests, but the students that failed are not bad students. Sometimes you are just having a bad day, but dont worry this will just make you extra prepared for the next test. Good luck!