@McKaka I feel like with men with smaller penis sizes I don’t enjoy it as much, mainly because I like when they can hit my cervix. Not sure if that’s an issue for you, when it’s smaller I just don’t enjoy it. But I’m able to cum during penetrative sex.
It sounds like you also may be in your head a bit, maybe have him focus on you in other ways and see if you can find a way to clear your head and focus on the moment.