How close am I getting and how can I go further?

Hopefully someone can tell me what I need to be doing to get past this tingly stage so I have detailed my sessions as best as possible.

There have been around 10 or so times now during sessions where I will get to the point of a warm tingly feeling building up for a few seconds and then fading.

But yesterday I was using my Nexus Revo 2 with the fast pulse mode while watching porn, it had been about 2 hours and nothing major had happened. Then I started to feel more sensation through my prostate, and had the tingly warm feeling build up, instead of fading within 5 seconds, my hands became tingly and were twitching (like a nice pins and needles), this lasted about 20 seconds and left.

The way I got there was by using the pulse settings on the second speed, lying on my back with my legs slightly raised and practiced flexing my PC muscles and holding them. This is what usually makes me feel sensations increase in my prostate. After doing this for a little bit I get semi involuntary twitches in my abs and occasional involuntary humps. After about a minute of this I start to feel a build up but quite often quickly lose it.

Any advice would be greatly appreciated!