How do I get my guy to be rougher with me? He slaps a little, gives a few spanks, but I need some real pain...

Sit down with him and explain that it’s something you need in order to feel fulfilled. Let him know that not only is it “okay” to be rough with you, but that it is actually preferred. Make sure he knows this is explicitly what you want and assuage any concerns he might have of getting in trouble or it being “wrong.”

After all, hurting someone who wants to be hurt is just plain polite and refusing to do so is kind of rude.