I was thinking of writing an article on this very topic and I came across yours. I think you've worded it perfectly. In my opinion, which is totally based on my own experiences and I'm not generalising, I think it's all in the mind.
A doctor, who has spent just 30 minutes talking to you and ticked some boxes isn't the right person to label you as depressed. But you believe him when he tells you that you need help. Why give so much importance to someone else's opinion of you?
The only person who is good enough to label you though, is you. But the problem is, we let everyone else and their lives label us, but we never allow ourselves to think of what and who we really are.
Most of it comes from comparison. In this age of social media, we have let ourselves run into this race of comparison where we can't actually accept the fact that someone else is happier than us, and just be happy for them. We start comparing their instagram/snapchat stories to ours and end up thinking how sad our life is. We start comparing our salary to theirs. Our boyfriend/girlfriend to theirs. Our family to their family.
Now the thing is, the comparison itself is wrong. The only person you need to compare yourself to, is the person you saw in the mirror yesterday. And if the person that you are today is better than the person you saw yesterday, there is nothing to be sad about.
So I believe it's all about the way you think.
If you train yourself to start thinking if things differently, if you start looking at the glass as half full and not as half empty, it builds a certain kind of mentality and thinking which makes you defeat any kind of disorder. It's all in the mind. And no pills can control your mind, only you can.