I dont know the official definition of depression relating to unhappiness. But my assumption is that when unhappiness becomes severe and chronic it becomes depression. Actually I don't think it matters what we call it, if it is interfering with your life, it is a problem.
As far as taking medication, it was an issue of how bad the depression got. When it became severe, I was willing to try medications. I know that medications cause side-effects in some people, but the side-effects are usually minor. Risk vs benefit. Is the risk of taking medications lower than the benefit that might come from the use of the medication. It is a personal decision, I think.
Anyway, my two cents
Rick