NANDA Defining Characteristics question

I was just talking to some of my classmates about this, and now I think I've confused us all. Over the last year, I've been writing my nursing diagnoses with information directly from the NANDA 2012-2014 book. My clinical instructor never mentioned anything about it, and so I continued on, thinking that I was doing it correctly. I now have a new clinical instructor, and what she requests from my diagnosis/related to/aeb is totally different from what I've been doing. I think maybe I've been doing it wrong all along.

An example of a dx would be:

Ineffective Coping related to inadequate level of perception of control as evidenced by destructive behavior toward others and high illness rate.

Everything above is directly out of the book.

My classmates are saying that they've been using their own related factors and defining characteristics, worded their own way, pulled from their experiences with their patients. Is this what I should have been doing, instead of using things word-for-word from the book? Are the related factors and defining characteristics just meant to be an explanation for the diagnosis, and are they to be used as a guideline for how you choose your own r/t and DC's? I'm feeling pretty dumb right about now.