It has been brought to my attention that there is a site called eBooks Tree, on which people are posting fanfiction that they have lifted from other sites. Several Inuyasha stories are there, so I would strongly suggest that you either search for your pen name or your story titles to see if anyone has posted yours without your permission.
eBooks Tree:
http://www.ebooks-tree.com/
In this post on another site, the author gives you the wording of a typical DCMA take-down notice, as well as instructions for contacting eBooks Tree to get them to remove your work:
http://chaneladdict.tumblr.com/post/116317924532
In one case, the person uploading the content specifically says that she doesn't own the stories that she uploaded... she just wanted to "share" another person's work. *eyeroll*
~~Wiccan~~