Small penis

Alright ladies. My boyfriend has a rather small penis (like, I'm talking like 3-4 inches.) and I'm wondering if anyone has any experience with a guy who has a smaller penis. I've been with other guys in the past and they have had longer penises. But I don't really know a good way to have sex with him and be able to get a good orgasm or at least something out of it. I will also add that we are both bigger people. What is some advice on sex positions and whatnot. He always falls out and it really kills the mood when he does.