It's no better when you're in your Sixties, as I am, and watch everyone going about their normal stuff and you're hurting. Seeing a rheumatologist leads to two possibilities: physical therapy or cortisone shots. Or both. That's all they know how to do. If you see an orthopedist, there are two possibilities: surgery or physical therapy. I'd just skip the docs and get a referral to physical therapy and see if it works. As for psychosomatic pain, you already know you have a disc problem, it's been diagnosed, so it isn't completely psychosomatic. But even if it is, it'll help to keep it moving and do something about it. In the meantime, if worrying is a problem, therapy is in order if you can't get a handle on it. You can always get the drugs if you need them, but it seems to me to be better if you can find an exercise program that gets you back to moving in a positive way since the drugs they use and the surgery are problematic. They'll be there if you need them.
Here's the thing about the back -- it can look fine and you can hurt and it can look terrible and you can feel fine. I've gone through a lot of back problems, and have learned that nearly everyone gets bad discs as they age. Most people don't get a problem from it, and nobody knows why some do and some don't when there's no evidence of a severe trauma, such as an automobile accident. Some of it is not the back itself but inflammation that could have started years ago from some trauma that didn't seem to be a big deal, but the body stayed inflamed until it couldn't take it anymore and you start to hurt. It's also true that it's estimated that 90% of the time back pain will resolve with no treatment at all in a short amount of time. So you're in an area where not much is known but a lot of treatment is sold -- sometimes it works, sometimes it doesn't, and sometimes it turns a short-term problem into a permanent one. Tough area. And it can be an area where a lot of pain is psychosomatic, or claimed to be so, because you can't measure that, either. Hopefully you'll learn some exercises from someone who is treating you that can help you recover and strengthen the area. But nobody can really tell you if it's psychosomatic or not, the science just isn't that developed in that area. And the above post is right in that focusing on the pain does make it more prominent in your mind, but the pain is real. I think it's unlikely this level of pain is all in your head, and you have evidence of a possible cause -- the real question is how best to treat it in the least invasive and risky way and come out the other side, and worrying about it won't help that any -- take it from me.
Some of the pain could be psychosomatic. You are focusing (perhaps hyper-focusing) a great deal of your attention on that area of your body. Let your doctor do his/her job in finding a solution, and try to keep your mind occupied with other things as much as possible. You want to avoid being hyper-vigilant, reacting to any and every pain or sensation you feel. Best wishes!