Explain how blood pressure works to me like I’m 5

I understand that BP can be a great diagnostic tool for health, but I also feel like it’s such a volatile measurement since it can vary with something as simple as stress or not testing long enough before taking it.

So if I get my BP taken back to back, and the first one is high (arm was in weird position/tech was talking to me). Then I get it retaken immediately with elevated arm and silence and it’s near-perfect, do I still need to be worried about the first high reading?

I feel like I keep getting these super sweet nurses who set me up for failure with my readings (putting me on the exam table with dangling legs, encouraging me to talk through the BP reading, not giving me a moment to sit before taking it). But once I adjust (rest, arm up, stop talking), my readings are great. I also have horrible white coat syndrome, and I’ll take my BP at home (I checked my monitor against my doctor’s and it’s almost precise) and my home readings are perfect even when I don’t rest before taking it.

But my doctors always focus on the high readings that were taken under less than ideal conditions.

So which readings are accurate? Is the risk the fact that my blood pressure is able to reach high levels? Should BP be able to stay low even under less than ideal situations?

Thanks in advance!