I am very strongly feminist and I am also a member of the BDSM community. Do I think there is a contradiction? The answer is a resounding "No!"
I base this on my belief that a woman has as much right to her own sexual identity, professional identity and spiritual identity as a man has. As an independent, strong woman, I have fought for equal rights and for freedom to make decisions about my body. I've been on the front lines of the fight to have access to birth control or to be able to abort an unwanted pregnancy, the fight to end sexual orientation and gender identity discrimination, and the fight for equal protection under the law. What I was really fighting for was the freedom to choose what I felt in my heart was right for me.
The way that I see it, as long as the activity is consensual - as long as the parties are adults and mature enough to decide for themselves what makes them orgasm and what makes them feel whole, that any choices a woman makes in pursuit of her sexual satisfaction is her right as a human. Whether a particular woman is Dominant or submissive, she is simply acting upon what makes her feel like a complete woman and is, therefore, exercising her feminism in the highest regard.