Hi Quiet Soul ~ For me, I knew I was depressed because everything always looked "gray" regardless of how I tried to be happy. I was always sad, glum, I got irritated easily, and felt like crying. This went on for a long tiime, without any breaks.
I COULDN'T stop worrying about everything. That was part of the problem. I made myself sick worrying. And i could NOT be happy & depressed at the same time. It was impossible for me. Getting a job didn't take the depression away. It might have raised the spirits a little,, but the depression was still there.
What helped me was going into therapy. There I found out WHY I was depressed, and it was clinical depression (major depressive disorder) and I was put on medications. My then therapist told me that because it was clinical, that I'd probably be on medications the rest of my life -- and it's proven true so far. I've had to be on them for about 40 years now.

I've been in therapy again since then, and that therapist agreed.
Also the therapists give you tools to help you stop worrying. What good does worrying do? It doesn't stop anything from happening. It doesn't change anything. All it does is make you sick! Once they can get you to believe that, you DO stop obsessing about things.
And turning things from negative into positive takes some work too. You have to look at things objectively and really take stock in things. You can do it, with some help from the therapist.
And you feel like crying because you don't know answers to alot of things or possibly you DO, but you don't know what to do about it. Past memories can haunt you, and can be painful -- you have to learn how to cope with them. The therapist can help you briing them all to a head and put them to rest.
I hope you will consider therapy as that was the only way I could have gotten better. It was the best gift I ever gave myself. Please think about it. I hope you're able to. God bless and please take care. Hugs, Lee