perineum increasing in size

Hello,

The p-tab is often not aligned. To prevent this I put my fingers just so it slides on the spot between my two fingers (it also align the aneros on the good spot). As I was doing my session with two fingers on my perineum, I felt the perineum getting bigger (more rigid) as I was feeling some kind of pleasure build up. At a moment I freaked out how much it was gaining in size and as soon as I lost the concentration on the contractions, it rapidly reduced in size (blood wasn't blocked anymore I guess).

The perineum region was retaining blood although my penis was flaccid. I felt I was very close to something but I wasn't able to go further as at a moment I stopped feeling much and I knew it was over as I felt the perineum losing of size.
Every peak of "pleasure" or sensation was accompanied of a rapid perineum size gain but I wasn't able to go further once the perineum was completely "erected". The feeling that something was coming would just go away after less than a minute. I tried a couple of time and was able to reach the peak of perineum "erection" but once I noticed something was different and I might be very close to the orgasm, it would go away... I don't know what I have to focus on.

Do you experiment the same thing? Is it before orgasm and if yes what do you do to keep going?

Cheers