Joseph, I am very sorry to learn about your suffering. The others have given you good advice-- except for avoiding psychologists. They can be extremely helpful. I know. I was lucky to find one once during a rough patch in my life, when I didn't know why I was on the planet and the center just wasn't holding.
Let's start with the assumption that there is nothing objectively wrong with you; but that you do feel deeply unhappy and wish that to stop. People come in all sorts of shapes and sizes, and with different life experiences; and we don't know now why unhappiness is in your portion, but it may be there for a reason that you will be able to understand later in life.
I think with Neptune-Mars square moon, one of your life challenges is in addressing feelings of depression. With the huge battery of tests you've described, probably someone has said that you don't have it, but a second opinion wouldn't hurt.
At the point in my life when I felt so miserable I could scarcely breathe, and I had to get through the week between psychologist visits, I found that taking small steps was helpful. Perhaps see if they-- or something comparable more in keeping with your life-- is helpful to you, too. I realize that "baby steps" may sound like so much superficial sublimation, but I think the universe recognizes when we make our own efforts on our behalf, and subtly starts to realign itself.
1. Learn some astrology-- it doesn't have to be much; and then try to be helpful to other people. You've reached out here. You can find many posts by unhappy people-- sometimes they just want an acknowledgement, a virtual hand reaching out to them. Engage them in a sympathetic way. You can be a real blessing to them.
2. List a few things that seem to ground or center you in a positive way. This might be your favourite soft music (try J. S. Bach-- he was into moods long before jazz was invented) or spending time in a natural setting, no matter how small. Slowly let go of some of your pain as you place your consciousness on the sound or sights. If you have some plants, imagine yourself breathing with them. If you can get near a body of water, sit and watch the waves. Or try meditation, or a yoga class.
3. Read Eckhart Tolle, The Power of Now. It is widely available, including in public libraries.
4. Take long walks. If your neighbourhood isn't safe, find one that is. Human beings evolved walking out of doors! I used to be so busy during the day that I took my walks at night-- with the dog. For some depressed people, walking in sunlight is as effective as medication.
Your 5th house sun will benefit from outdoor recreation!
There is a lot of good in you. You sound like a gentle man who doesn't want to hurt a fly. This is a gift that you can convey to people in need. You've been there, and have developed compassion.