In a somewhat selfish way, I'm glad to see you're still alive. I just wish the suffering didn't go along with it.
I've given the situation a lot of thought from the perspective of the medical provider, and maybe this will somehow help you in not feeling "abandoned" as a human being. Maybe not, but I'll throw it out there:
Your condition is obviously very complex ad multifaceted, and in your specific case apparently on the more severe end. Not enough funded research has taken place to give a proper evaluation of treatment modalities that would otherwise be available for other, more direct conditions. Our teaching and practice, both medicolegal and safety reasons, dictates that we follow (or at least begin with) the most commonly accepted protocols before we move into something more experimental. Additionally, there is always the fear that the risks of certain treatments will exceed the benefits; in a case like yours, the medications have plenty of side effects, and it's unknown whether they'll help you or make you worse even in the absence of side effects. Furthermore, a doctor should be able to know when to say "I don't know" and defer to more specialized experts - I can tell you that some of the worst doctors I've seen were those who were too arrogant to admit they did not know something, and thus caused more harm.
Now imagine a case where a doctor would prescribe you a treatment which hasn't been well-researched, and it causes you further debilitating harm that makes you worse or even causes death. This is enough for the provider to lose their license in the snap of a finger. They'd have to justify the use of a completely off-label treatment modality, and likely would not be able to do so. Losing their license would mean that they're not able to help the numerous other patients that they would be otherwise be treating for year to come. In other words, many patients would lose the care of their doctor because they messed up a single treatment on a single patient. The net cost of this experiment heavily skews towards the negative.
(I'm not even going to get started with medical insurance companies, because those are just a terror. They're greedy middlemen who, as a whole, make patient's lives more difficult and doctors' lives more difficult. The damage they do certainly exceeds those times when they actually end up helping someone.)
Anyway, what I'm saying is that in the case of at least some doctors, it's not that they don't care to help, but there's an inherent fear of excessive harm. It's even an essential part of the Hippocratic Oath to "do no harm." We want to be able to help as many people in a positive way as we can while minimizing the harm we cause. As a result, there are people with undermanaged complex conditions like yours, with no recourse. Here, I must agree that this is a terrible consequence.
Ultimately, your own pain and suffering is yours, not somebody else's, and from your perspective, it's obviously you who should be treated for your own medical problems. It's something that any human being with the slightest bit of empathy should be able to understand. Your suffering cannot be dismissed.
It just poses a very difficult ethical problem. The bottleneck of you having to wait for treatment at a specialized center (which you've spoken about in the past) just makes things even more difficult, because there is a light at the end of the tunnel, but it's exceptionally far out given how much worse you seem to be getting. I just hope and wish that you'll be able to find the strength to get there in time to feel improvements.
Thank you for sharing here and finding the strength to let us know that you're still with us. It was you who led me to read more about POTS, rapamycin, etc. I believe patients can truly be excellent sources of information and learning for open-minded doctors who take the time to listen.