My husband and I have been married for 12yrs and it got to the point of avoidance. I think it's excellent that you're seeking help and women are able to help you without judgment. Look for vaginismus and your hormone levels, but if all is OK, it's psychological... petite or not. I'm tiny and what I do is relax so it's easy for him to enter without shoving it in.. you have to make a concerted effort. When he starts thrusting harder though , because the pain doesn't just go away, I mentally escape, like I mentally picture myself at the beach and distract myself that way, it takes your mind off what he's doing and you're relaxed. He's happy, then he makes you happy afterwards.