What does a p-wave actually feel like?

Still a beginner, had a handful of sessions now. Still unclear on exactly what a p-wave and involuntary feels like. I have a Helix, but don’t actually feel very much when it’s in me. I cannot tell whether it’s actually making contact with my prostate. I’m not sure if the mild pleasure I can eventually reach is from prostate stimulation, or just getting in the mood, breathing pattern, and clenching.

I do sometimes get a little pulsing feeling that doesn’t feel like the Helix is moving or feel it against my prostate, but feels more like I can sense my pulse right on my butthole. Is that anything?

I can get to some voluntary quivering of my body, but I’m not sure if I’m on the right track. I see lots of people talking about p-waves and involuntaries, but what should they actually feel like? How much movement does an involuntary actually have?