I have had very similar symptoms as described in the first post for the last 9 years.
My advice is unfortunately to be very sceptical of people who claim they have the answer to your condition.
The truth is that modern medicine is still very much in the dark ages when it comes to a lot of chronic fatigue related illnesses. By definition you have ME/CFS because your doctors can't pin your cluster of symptoms on anything else. It is a diagnosis of exclusion & sadly has no overly effective treatment.
Eventually I discovered the worst of my symptoms (daytime fatigue, weakness, brain fog & decreased exercise tolerance) were caused by the fact I wasn't sleeping properly at night. I could be "sleeping" for 14-16 hours but not getting the deep sleep that your body requires to restore & recover.
I have since started on Mirtazapine & Melatonin at night which helps me sleep much better than I previously did. This has in turn, improved the above symptoms, though I am still very restricted compared to my previous level of function.
I have also found that adequate hydration has helped with a lot of my symptoms. I force myself to drink more than I feel I need to & remarkably feel better shortly afterwards.
Again, I'm not saying this is the answer to your problems as we may both have completely different triggers for the same cluster of symptoms. However I felt compelled to respond given how similar our situations were & I hope you can find something useful in it.