You picked a tough time to try and break into the paper book business. Kindle and other ebook websites are in the process of killing off traditional publishers. They are going to do to them just what internet file sharing did to record stores. Did you think that Borders would vanish? Did you think that Blockbuster would go broke? How long do you think Barnes & Noble will be around? I love B&N and I love physical books but I can see that they are going the way of wind-up record players.
Publishers are scared and are not signing up new authors in such an uncertain market. I would recommend that you read the last twelve issues of Writers' Digest Magazine. They have many articles on how to find an agent, internet publishing, the state of the industry, etc. There are also books on all these topics and many blogs on internet publishing.
The fact that your novel has an S&M theme (or subtheme) means that the book will be considered an attempt to cash in on the 50 Shades phenomenon. The fact that you were writing on it before 50 Shades came out is irrelevant. That may not be fair, but that's life. Being first matters.
Good luck. Remember what Billy Crystal said: Writers write.