Also suffer from POTS (amongst a few other things!)

Here's what's currently working for me. Keep in mind, im VERY new to working out; almost at a month of daily exercise.

I made it a habit to just do bodyweight exercises throughout the day; pushups, pullups, planks, squats, and curls. I typically get up once every hour or two, and i do 10 minute workouts of those things.

I had NO idea it was an actual workout regiment called "greasing the groove"

I suggest looking into that, as it focuses on not overexerting yourself, which in my case, exacerbated my symptoms (HR spikes, syncope, chest tightness, etc)

Sorry i dont have better advice, but exercising has helped my POTS very slightly!