Fit & Technique??

I bought a MGX about 3 weeks ago, my first attempt at "this sort of thing." Found it easy to relax into the fit and to do the breathing exercises, but I have not had much sensation. Mostly feel the the perineum tab and some fullness, but no real direct stimulation of the prostrate.

Last night, after about 90 minutes, I was lying on my right side and reached back to the insertion ring and pulled the MGX out about 1 inch. When I contracted, I resisted letting the contraction draw the business end back into my rectum, and I felt the thick part of the head pressing against my prostate. Very strong feeling! I continued this technique, feeling a powerful massage of the prostrate, but only if I held the unit to prevent it from going all the way in on the contraction. Note that I did not push it at any time, but allowed the anal contraction to do the good work. I did not experience any involuntaries, but I did feel that I was leaking (I wasn't, but the feeling was there). I plateaued and then sat in a chair and masturbated. Incredible woodie and orgasm, but this is the Traditional O, not what we're after.

I am 6' tall, 60 years old, trim and in excellent shape. I do not have any prostate enlargement, but I do notice an age-related slower and thinner urine stream. Does my experience mean:

1. I should try the shorter model (SDX) so that the head will be better positioned?
2. I should try the thicker model (Helix)?
3. My technique of holding preventing full insertion is wrong?

Please advise! And thank you for the Forum. Incredibly helpful!!