From what you've written i actually don't think all she wants is sex - she just seems frustrated, as you are. This issue has been going on for a year. What i can't discern is whether you have a naturally lower libido than her anyway and so this issue is creating even more frustration for you, or you simply can't bare the thought of a good thing going downhill and not knowing what to do about it. Are you seeking further treatment? I suppose ultimately it comes down to whether she can be patient and supportive enough to see through a solution with you.

I definitely think you need to talk to her. Good luck.