The official stance from my psychiatrist was, if you have times where nothing seems that interesting to do or there is no motivation to do normal day to day act

The official stance from my psychiatrist was, if you have times where nothing seems that interesting to do or there is no motivation to do normal day to day activities, and that happens regularly (once a week) then you're clinically diagnosed as having minor depression. If you have those several times a week it can be major depression.