Is it possible to be diagnosed with depression by an NHS counsellor?

I am chronically depressed and have been so for some years now; I have never been diagnosed unless you count the numerous stints of therapy I have undergone in which they usually had me take the standard questionnaires which would declare me "moderately depressed and severely anxious" - and this is probably because I have no intent to take my life and have always been passively suicidal.

what I'm asking is, is it even possible to actually be diagnosed as clinically depressed when free therapy services are normally short term. I don't believe I have ever been with a therapist long enough for them to make that assessment, which is why whenever I have to fill in a form and it asks me whether I have a mental illness I say no since I've had no formal diagnosis