Check your LBS and see if you can get your bike fitted. I went to a guy that measured all my joints and set my shoe cleats and bike at the proper angle for time trials. He worked with the LBS and ordered the proper length stem and aerobars. Perfect the first time. Unbelievable! He also gave me riding tips re. body position, breathing, etc.

Here is the guy I went to, maybe there is someone like this in your area: www.wobblenaught.com

You could also try moving the seat forward, but that would change your riding angle. But, if you are already in a relaxed back position, moving forward might not be bad.