Have orthostatic hypotension drink a gallon of water a day with sea salt peeing a lot and still feel blood pooling when standing bloodwork normal?

It sounds like you: are trying to do the right things but sometimes your body needs a little extra help. Good quality support stockings thigh or waist high worn all the time would help. There are also medications that may be useful (Florinef, Midodrine, Droxidopa.) If your primary health care provider can't help then see an electrophysiologist or university specialist.