I'm pretty sure there is no diagnostic test for ME/CFS. What are you referring to?
Also I don't understand how semaglutide did help you while you're at the same time part of a minority risk group with a hypersensitivity to it. Isn't that a contradiction?
There are now a number of very definitive tests, most related to immune system profiling. Prof. Ron Davis has some good research and has shown that plasma from someone with ME/CFS when combined with normal red blood cells will greatly diminish the ability for red blood cells to handle stress (pumping out salt).