Ass-fucked

A while ago, i had asked Lady Helena, what toy or device She would like to use on me if She could have any device She could wish for. Her answer was surprisingly simple, She wanted to fuck my ass...
I already had built the prototype of my remote-controlled fucking-machine at that point, so adding the final touches, like a vac-u-lock adapter with a bigger dildo didn't take long. However, until now we hadn't used the machine, we had always done other fun things during our sessions.

I was a little nervous before the call, because although i'm very used to wearing butt-plugs, i had never used the machine for longer than a few minutes during testing and also when i use a dildo on myself, i usually loose interest pretty fast. I knew that i was in for a new experience and knowing Lady Helena, i also knew that it would get intense.
She had told me that She might allow me to cum and i really had been looking forward to it. She allowed me to stroke while She controlled the speed of the fucking-machine, but when She started to have me repeat sentences about why i don't deserve to cum, i was very surprised. Had She changed Her mind and i would be denied after getting fucked in the ass?
She told me to stroke faster while She increased the speed of the machine, too. The unused sensation in my ass was getting a little uncomfortable, but after changing my position slightly, i managed to get comfortable again and enjoy it.
Lady Helena started to count. She told me to get closer with every number and on 22, i would be allowed to cum. I knew that it wouldn't be that easy, so i wasn't surprised when She started over at one a few times. It was a surprise when i finally heard Her say '22!'. I hadn't expected it and it took me off guard. I was cumming automatically without even trying to and it felt awesome while getting fucked.
A new sentence popped up for me to repeat: "i don’t deserve to cum, because it is not allowed to think about an orgasm - and i just did."
Had i just done something wrong? Judging from Lady Helena's giggling, i had just fallen into Her trap. I started to worry...
After leaving me puzzled for a moment, She revealed that She had originally planned to stop at 21, but changed Her mind and allowed me release. I had done nothing wrong and She was only being amused about my confusion. She is so generous to me!

I'm already looking forward to the next time getting fucked (i'm already thinking about some tweaks for the machine), but the next session will be about testing my pain threshold and before that, Domina Shelle wants to try and make me cum from nipple-torture...