positions for smaller penis

Okay y all...My beloved husband is on the smaller side. He's the only guy I've ever been with so I don't know anything else. We've been together 2 years and we are trying to conceive our rainbow baby. I want to try some new positions but all that we can get down well are missionary and from behind. Whenever I try to ride him he slides out constantly and it's just not that good. What are some other things we can try to spice it up?!?!