Mr. Physics, have you ever had your Norepinephrine (NE) levels tested? If not, I urge you to do so. High NE levels on standing is the Hallmark of Hyperadrenergic POTS (H POTS), and this type of POTS is treated differently than the other types. It is important to know your type for this reason. For example, salt is not recommended for this type, and recommended meds are Clonidine or Methyldopa.
H POTS is the type that has been seen in my family and is genetic. Those of us with H POTS have some problems that are not seen in the other types. You can do some reading at the link to a Vanderbilt page I will leave. On the left of the page are some links, and I would urge you to have look around at the info they provide. https://www.mc.vanderbilt.edu/root/vumc.php?site=adc&doc=38882