Help me!!

So my boyfriend and I have been together for almost 6 years. I am very into him being dominate, slapping my ass, pulling my hair, just being rough and dirty with me and he won't do it. I've tried asking him a few times to do this and he just doesn't. Our sex is starting to get very repetitive, for lack of a better word. I don't know if this is a factor, but I feel like he has no sex drive. I am constantly Horny and I start to drop hints and make moves so he knows, and 9/10 times he ignores them. I also lose all confidence I have when we start having sex. When he askes me how I want it, I freeze and don't know what to say. Can anyone help me with any of this?? PLEASE??