Questions about using wrong muscle groups and ways to improve

Hi all,

I'm a little concerned that I'm activating the wrong muscle groups during my sessions,
and I hope that the more experienced users here can point me to the right direction.

The following are the progress I have made so far.

* I had occasionally used Aneros devices with not much sensation for several years.
* Last month I got the Peridise, and after about 2 sessions, I start to feel that I can intentionally induce involuntary anal contractions which induced rock hard erection. It was much easier to do then using a standard device than say MGX.
* In the middle of one session, I switched from Peridise 18 to MGX, and the involuntary anal contractions grew into a series of muscle contractions. Those contractions felt like all my muscles and and circulation system were controlled and lead by my prostate, but that sensation didn't last too long.
* Since that session, I have not been able to feel the same automatic contractions lead by the prostate.
* Since that session, I can feel horny and intense pleasure as soon as any Aneros device is inserted, and the pleasure can trigger erection.
* Since that session, I have learned that I can induce automatic body shaking and hip thrusting to bring me close to / or reach possibly mini-O's (prostate and muscle contracts without ejaculation plus high heart rate) or wet ejaculations. The mini-O's and wet ejaculations felt ok, not spectacular.

After examine the automatic body shaking and hip thrusting with a few more sessions,
I found that I was actually activating my lower abdomen (core) muscles to lead the body shaking and hip thrusting
I think I can do that because I have very strong core muscles from practicing yoga.
However, I also found that these core muscle lead body shaking and hip thrusting can actually reduce my mental focus on my prostate, and also reduce the horny sensation originating from the prostate.

Since then, I have tried not to activate too much lower abdomen core muscles to limit the automatic body shaking and hip thrusting, which let me focus more on the sensation of the device rubbing my prostate.
I can occasionally start a few involuntary anal contractions here and there, but I have not been able to induce that prostate-lead contractions anymore.
Without more intense stimulation, I can not reach any O's or ejaculation.
That makes me very horny but also frustrating without orgasm or any sense of release.

Can someone please give me some advice on what I can do/practice/change in my sessions to improve and get back to the "right path"?
(Actually I don't even know if I'm on the right path or the wrong path...)

Thanks