Can i tell ye one thing and not boasting

As the subject came up on Similar Worlds and i don't even understand it myself -
Im after suffering so much in my life from 14 right up to 41 and i never suffered from depression not once . I don't know why .
It's should of hitting me hard but never did .
Could some describe to me what depression actually is from a symptom point of view cause i don't really know or is it what my problem is that im totally numb all the time