Hmmm, I have low BP as well, nearly as low as yours, actually, but I'm 5'4''. All of my previous doctors have checked to make sure it isn't causing me problems (it doesn't, I have fainted a few times in my life if ill and if I get up too quickly, but that's about it). None of them mentioned a height connection though.
My GP here commented on it, and made sure to put a highlighted note in my file to make sure it was taken into consideration if I went on any medications (at one point I needed a beta-blocker for something, but they can lower BP). Can you ask for a 2nd opinion? No one has ever tried to raise my BP as it wasn't causing me any trouble, but they are all very careful to keep it in consideration.
Also, isn't it nutritionists that don't need medical degrees? Whereas dieticians do. That might be something to consider.