He's average size

Doggy Style Position
How to do it:

You kneel on all fours; he stands behind you and penetrates, holding your hips to move you back and forth. Vary the technique by lying facedown, flat on the bed, with your legs spread apart while he lies on top of you and penetrates from behind. If you’re feeling adventurous, try it standing up with him standing behind you and penetrating. Then, lean forward until your hands touch the floor. If it feels like he’s penetrating too deeply, lift your bottom.

Why you'll love it:

This deep penetration is deliciously primitive because it’s the way animals do it. It’s him at his most dominant and you at your most submissive and vulnerable -- which plays nicely into any similarly themed fantasies. The rather pleasant sight of his penis pumping in and out of your vagina visually excites him Your bottom presses against his testicles for additional stimulation, and your orgasm feels extra intense because he’s hitting the sensitive part of your front vaginal wall. He can also easily reach around to play with your clitoris.