He's on the small side

The Hook Position
How to do it:

You lie on your back with him on top of you. Hook your legs up over his shoulders for deeper penetration, giving him complete control.

Why you'll love it:

If he’s not terribly well-endowed, it’s a good position for maximum penetration. A tip to remember for this and other positions: Crossing your ankles (in this case, behind his neck) helps tighten the vaginal canal. It’s also a great way to squeeze him in and make him feel fuller inside you. His scrotum brushes against your bottom with each stroke and you can reach forward to cup his testicles while he does wonderful things to your breasts with his hands. The blood will rush to extremities like your nipples, making them highly sensitive.