Hey, he doesn't have to get sensation through his prosthesis to be satisfied (though I'm willing to bet he gets some pleasure from it). Can I assume you are female? Correct me if I'm wrong. I'm pre-T and haven't had any bottom surgery. So for all practical purposes, I have female-style orgasms. I don't know what it feels like to have a real cock, but I know with my current equipment, there's no "real" that I need to live up to. My getting off often depends on set and setting, circumstance, imagination, scent, emotions, words, etc. I don't even need any touching to be in any certain place. And my orgasms are pretty open-ended. There's no gunshot beginningendoveranddone kind of thing. I think you and he can both be pretty satisfied with no matter what your sex looks like, as long as it makes you both happy.
I wouldn't worry too much about defining things or having expectations. Just play, and talk to him about sex as much as possible, so you can figure out what you want and how to enjoy one another. He's just a normal human, and even cisguys can be pretty confusing and quirky.