New milestone reached?

So my last 2 sessions have been a pretty good success in my opinion. Both times I started with a program for about a half hour to get me warmed up. Then I switched over to my knockoff njoy wand. Started on the little ball side for about 20 minutes. Took it out, then cleaned it quick and used the large ball end and slowly went over the prostate area. Then went to a slow-normalish pace for about 10 minutes. Soon after my heart rate skyrockets, and it involuntarily clamps down on the toy and I can barely move it.

I can feel my pulse in my stomach area while this is going on. I'm pretty sure it's an orgasm, but I dont have any recognition of pleasure other than the symptoms of an orgasm.

Both times I cleared my mind and imagined a hand massaging my prostate and the girl wearing some lingerie that turns me on. But no sense of pleasure even when I'm open to my body responses.

With all that being said, I do feel as if I'm on the right track. The wiki milestones list one as involuntary clamping without pleasure. Any suggestions on how to improve? Is it one of those acquired pleasure feelings that just takes practice to learn? My journey started in last February if that helps.

Also I played around with my nipples after the last session and it felt like rushes of vibrations running through my body to my crotch area. I'm still trying to learn how to get off with just nipples and definantly made some headway imo.