Me, too, exactly. I bought a quality BP cuff and it never accurately measured my BP which is low. I would do one arm manually or have my RN husband do it, and use the automated cuff on the other arm. My BP doesn’t vary that much between arms, and I'd get something like 74/56 manually, and 118/70 with the automated cuff. I have the same experience in medical settings. "Oh look, your BP is great!" when I was talking when they took it, and just came in from traffic and aggravation, AND they use a machine. I think they are good - I used them as an EMT - but not meant for those low (or high?) readings.
The problem is that they always want to set me up with a 24 hour monitor - that would make me look like a liar since the readings would be inaccurately high. I have charted hourly BPs for more than 24 hours.