Help with technique

I was new to butt stuff in general when I bought my progasm jr a couple years ago, and I’ve only recently started really using it in earnest. When I first insert it, it feels like it punches my prostate. It’s a short, really intense burst. I wouldn’t mind if the rest of the session involved that but the sessions are usually okay at best. It might be that I don’t know how to psych myself into a heightened sexual state and that’s what my rewiring will be, but I feel like it’s possibly also my technique.

I have very strong kegel muscles and have no problem flexing and holding, but I feel a greater sensation from flexing without the toy than I do with it. Without it, I get a buzz in my pelvic region and a fog in my head. With it, it feels like something is just shifting around slightly without stimulating much. I usually give it a few dozen pumps, sometimes holding it for 10 or 15 seconds, expecting something to build up. The initial punch from insertion feels much better than the lax sessions that usually follow.

Am I doing something blatantly wrong, using the wrong toy, or something I haven’t thought of? And should the toy (to stimulate the “punch”) be shifting in and out of my ass or (as it usually goes) is it supposed to stay fully inserted?