I didn't class mine as panic attacks either, but the doctors don't think the extremity of the physical symptoms are what matters. I go very, very still, tense some parts of me - say half the fingers on one hand, I almost stop breathing, and sometimes get very teary. In my head I am completely stuck in a panic loop, wanting to be left alone, to be somewhere else, to the point where I cannot interact. I don't get racing heartbeat, sweats or much else, but my brain is full-on trying to stop a physical attack by freezing like a rabbit in the headlights.