Your boyfriend sounds like a real ladies man. Does he use a fork when he eats? Does he wear shoes or just roam the streets on his callused soles? My answer to your question is simple: Voice your feelings and needs to him. Sex, and all the touchies leading up to it, can improve if you openly communicate. Perhaps you're intimidated or embarrassed to discuss your needs with him. I would ask you: Do you share your needs with your man when it comes to other things? Why did you watch The Last Airbender five times this weekend? Because you liked it, or because you didn't want to upset your boo? Do you wear a push-up bra to bed because it's comfy or because "Frank" wants you to? See what I'm getting at.
The world of sex can be your oyster sauce if you both can articulate what it takes to get you juiced. Maybe he's not "selfish," just mad ignorant. So talk it out. That's the key: massage your communication skills and he'll be massaging your back and talking in your ear in no time.