Question

I have a question about sex. About sex and S/M. Because I've been pushing my girlfriend to give some pain while we're making love. Not all the time but when it happens I have the strongest orgasms. Last night was no exceprtion. So I've been wondering if I'm the only survivor with this sexual kink. Because I can't help thinking it's bad to want the pain, to need it sometimes. It's like I'm in my body, for once, you know? And I'm feeling every second, not just seeing it or hearing it. I'm living it. There's no distance as there can be at times during regular sex. Is that normal? Or at least common?