Boundaries between having a disorder or not are always somewhat vague, partly a result of inclinactions the person who diagnoses you and symptoms overlap. Moreover, depression or anxiety disorder can be the result of difficulties you experience because of another disorder.

Personally, I believe a diagnosis should be a handle that gives you access to a better suited treatment. That could be the correct medication (for instance for BPD), a specific flavour of psychotherapy or other forms of support.