This doesn’t sound like POTS at all. Low BP is generally considered anything below 90/60, although it can vary for some people. Your resting HR is pretty low, and even your standing/active HR isn’t too bad, so the brief spikes up to 100 could just be lack of exercise or sudden bursts of movement. With POTS, your BP should be low on standing, your resting HR higher, and your standing HR at least in the 120s. I would ask your doctor why they put you on that med. I’m not a doctor, so there may be another reason they prescribed it.