My dad is a doctor he took my blood pressure recently. We were surpised to see that it was high 140/80 ish...
he tried a larger armband as my arms are quite chunky from the gym and pizzas and the next reading was 120/70.
you do sound very nervous heartbeat 120 at rest in the surgery!!! thats like me jogging!!
He says that the size and fitment of the arm Cuff is critical for an accurate reading.
hope that helps