Yeah, that's exactly my experience. I'm sorry you've found no solution in a decade, I can fully understand wanting to try desperate measures, I think I'm moving closer towards that too. Other people wont understand though.I have the same story. I had one summer at 22yo where I had a normal libido, and never again since. Sometimes I wish it had never happened so I wouldn't have spent almost a decade chasing after getting that feeling back.
My best guess is high prolactin. I have had above range prolactin on a blood test. I don't know what causes it or cures it. I've tried almost everything. I might try cabergoline as a last ditch effort even though it's a bit dangerous, after which I'm giving up on the matter altogether.
Standard recommendations for you: sunlight, carbs, easy to digest food, lifting/squats, etc.
Have you tested your prolactin levels? What were they like?
Spent a summer sunbathing almost every day for an hour. Felt nice, but no health improvements. Been trying different amount of carbs, from zero to a moderate amount (never really tried super high carb). Actually, doing a zero carb/carnivore diet seemed a bit promising, but it wasn't sustainable at all, I ended up undereating (too expensive, not palatable enough etc). Went from sedentary to going to the gym 6 days a week, still no health improvement.
Right now the only thing I can think of is this either being a hormonal thing (not enough testosterone, too high prolactin like others mentioned, etc), or something to do with allergies/the immune system.