Briefly, the missionary position is extremely weird and uncomfortable for me, I have no idea how to function in this position. I am leaning on top of the girl, trying to support myself with my arms (which gets exhausting after a few minutes) and simultaneously trying to thrust. Now when I'm thrusting, it feels more like I'm moving my entire lower body; the penis is "somewhere down there" and I'm not stimulating it that much.
The issue is that I can't get any rhythm going in this position, which would allow me to concentrate on my penile sensations. It's either not moving at all, and stationary inside the vagina, or it slips out, or I can't move in/out fast enough, because it's unnatural to stick my butt out with such frequency. All this time, my arms are getting tired, but I can't just lie straight on top of the girl, because then I'd feel my penis even less.
The position that works relatively well is doggy style. In that one, I have something to lean against (the girl's butt) as I'm building rhythm and pressure. In missionary, I can't lean against anything. Also, with my upper body upright, I'm better able to focus on the penile sensations and tense my muscles as necessary.
What's my problem? How can I make the missionary position work for me?
The female supine-male prone, face-to-face position is not unknown among lower animals.
The female-standing, male-standing, she leaning over forward, rear-mounting position is clean: you can copulate anywhere that you will not offend others, such as family restrooms. She will not get dirty, muss her coif, rumple her clothing. If she is taller in reference to her vaginal height when bent over and his penile height, she can kick her shoes off to lower her vagina to a more comfortable height.
Wearing a skirt is most convenient as all that need be done to get ready is lift her skirt and lay it on her back. Any spillage won't soil pants if she is not wearing any.
Added non-copulatory benefit: a skirt is a portable pissoir that she takes with her everywhere. Find a private place behind some bushes, squat and do her business.
Plenty of ventilation and her p***y won't smell like a wet cat. Surely we won't ever go back to full-torso one-piece girdle-corsets that wouldn't open underneath.