With him kneeling, the trick to this position is finding something slightly lower than his hips to prop your sweet ass on, like a sturdy coffee table or a pile of pillows. Sit on it and make your legs into a V-shape. When he has to enter you downward like this, it keeps him from going super deep. You get the feeling of being well-taken (oh yes!) without being impaled.
2. The cherry on top
Lie on top of him on your back and have him enter you from behind. This position has a semi-awkward angle that keeps him from hitting you too deep, but still strokes the sensitive top side of your vagina. Even better: lube your upper thighs so they stimulate his shaft with every thrust. He also has direct access to finger your clit from here, which is always a bonus.
3. The stand and deliver
Stand facing each other and lift one of your legs, wrapping it around his waist. Have him enter you standing like this (he may have to squat a little). One of the disadvantages of standing positions with a man less bountifully endowed than yours is that you just can't...get...him...deep...enough. But that's the good part here. You'll get plenty of him, just not too much. Part of this is because you're lengthening your vaginal cavity, but don't bring that up during. Or ever, probably.
4. The tight-high straddle
Hard to imagine that something that starts with sitting cross-legged could be so hot, but trust. Have him sit cross-legged on the bed and straddle him, using his raised thighs to support your butt so he doesn't go too deep. You control the thrusts (control = good): go slow and rock back and forth, letting him slowly in deeper. Also good for deep, hot kisses, plus you'll have a free hand for self-love on your clit.
5. The humping bumper cars
Warning: this position is not only way advanced, but involves being in that crab walk position from grade school gym class. With him in the crab walk position, stand straddling his hips, squat down to let him enter you, then lean back onto your hands so you're in a crab walk position too, with him inside you. Yeah, it's kind of funny seeing each other doing a naked crab walk, but you'll both forget that immediately when you lean back and start thrusting against him.
So, dare to try? I think it won't hurt even if your partner just has a normal kind of penis, just don't forget to always keep it safe!