The two main traits in narcissistic personality disorder are lack of empathy and grandiose sense of self importance. These ought to have been present through out your life and not only on certain occasions. It is generally a good idea to have the personalty test administered by someone experienced in it although you can use online formats to complete the questionnaire.
CBT (cognitive behavioral therapy) is one of the modalities used to help an individual manage their symptoms as there is no cure per se for personality disorders.
Malignant Self-Love: Narcissism Revisited Sam Vaknin