Salt, hypothyroidism, high BP and fluid retention

I have been on blood pressure medication for a few years and although it has lowered my BP (initally 180/105), it´s still borderline high according to GP (never < 130/90 in doctor´s office). I also tend to retain fluid and look puffy. My GP says that is what you´d expect in someone who eats too much salt and has recommended I switch to low sodium table salt (iodized). I gave up on table salt years ago and now only use Celtic sea salt (also said to be good for adrenal health) or Himalayan salt. My GP says all salt will raise blood pressure and it´s the amount you consume that´s important, not the type. I should not use more than 2 tea spoons of low sodium salt daily in an attempt to lower BP and reduce the fluid retention. I always get the "too much salt is dangerous" speech...apparently, my GP considers anything above 2 tea sppons daily "too much". To me, the advice to eat table salt sounds as crazy as the advice to eat margarine instead of butter back in the 1970s...

However, it seems both highish BP and fluid retention can be caused by low FT3 levels at cellular level which of course cannot be measured.

I am reluctant to use table salt of any kind and would like to know if others have experienced the same problems and found them to be T3-related?