The word 'syndrome' is one applied as a medical term to a cluster of signs and symptoms occurring together to describe a specific abnormality. Good science is always backed up by a large body of properly researched evidence gathered over many years. That's why the DSM is not an annual publication.
So what is FMS exactly?
The False Memory Syndrome Foundation describes FMS as “unfounded allegations of childhood sexual abuse based on recollections of previously repressed memories.” To put it more plainly, they say memories that a survivor has cut off from conscious awareness or dissociated (pushed into the 'deep freezer' part of the mind) in order to survive, and then remembered (when safe to do so) are in reality inventions implanted in their minds by over-zealous counsellors, books and survivor stories.
REMINDER: Memories only come back when you feel safe enough to remember, and your psyche is strong enough to withstand the process.
SUGGESTION: If at some point you decide to take your abuser to court, and he uses the FMS defense, try and get a top-notch trauma specialist with impeccable credentials as expert witness.