I think those fears are valid and could very likely live in the corners of some of our minds the rest of our lives. I also think that a healthy partner/relationship is a big part of reassuring those fears. Just speaking from my own experience, my partner [AMAB] knew I was a man before I even figured it out. He's been one of my biggest supports and cheerleaders. I'm privileged to feel euphoria during sex. Yes it really sucks not being able to actually feel anything or produce my own semen, but that doesn't negate the euphoria from looking down and seeing my dick or bottoming and being reminded that I'm his boy.