A blood pressure of 90/60 to 120/80 is generally considered normal. The numbers you report seem to be in the normal range. It does sound like you have tachycardia, though. As bombshell noted, with POTS you get an increase with a change in posture. If that's not the case I'd look into inappropriate sinus tachycardia (IST).
And Steven is right about combining a beta blocker with something to keep up your BP. If it is on the low side of normal, that might help.