As a 1 year+ non gainer myself I was reading this thread like someone read a drama book waiting for the happy ending, which in this case didn’t happened (yet I hope).
And you made a great point when you said we non-gainers have something in common, I’m exactly like you said: “Overly obsessed or dedicated, difficulty taking good advice, jumping around trying different things etc.”
In my personal PE career I think my issue was overtraining, so I will try going lighter now and I’ll update you if any progress.
You obviously know way more about PE than I do, but since you said you’re open to suggestions, I will make a few:
1º- Stop testing with pumps, throw that away if necessary, IMHO you tested way too much with that already, explore new areas, that I hope will do good both to ur mind and dick.
2º- Stop over focusing on girth, focus on ANY gain (even if flaccid gain) and keep doing whatever generate that possible gain.
3º- I may be wrong here but I think you are underestimating the power of heat, do warm up and do your PE while applying sort of heat (like idk manual stretch while in a hot tub or running hot water from shower, then getting it back to room temperature while holding some stretch) [to be honest I think this was one of my biggest mistakes on my 1 year career, not caring about proper heat]
4º- Eat more/better and take random vitamins, not to get in shape in order to get gains (its irrelevant, I’m a powerlifter jacked with 6 pack and I haven’t gained nothing), but to try replenishing whatever the hell our dick needs to grow, so in the worst case scenario (not making gains, our case) we don’t feel like we wasted time, we feel like at least we got healthier by eating better in a pursue for gains, which is a good reason to eat a lot and take vitamins, we probably wouldn’t do that just to get healthier but we easily would do it for the so wanted gains!
Those are the things I have in mind for now, because those are also the changes I’m making in my routine.
One question if you don’t mind, what’s your age?
No need to be specific if you don’t want, you can say 3x or 4x or 5x etc.