If your BDSM is 'only' (nothing wrong about that) about the sex and your sex is centered on intercourse and/or your genitalia then you're ... well ... screwed. Or not, as is the case.

But there are tons of other ways to keep the dynamic going, even during your period or outside of the bedroom. Also, you don't necessarily have to get out of your clothes to be Dominant and submissive, no matter who's the Dominant part and who's the sub.

There's really no limit to your imagination, just make sure it's safe and sane and consensual.