Are you able to make the bindings any bigger? I'm not familiar with burton bindings, but Ride bindings have the ability to "open up". There are multiple holes for the screws that hold the bindings together, and you can move them to the largestest setting. I would first look to see if you can do this to your bindings and if you can see if that helps you center them.
If not, and the bindings are positioned on the board as far back as they go, you will need to get a wider board. Not necessarily a longer board. A lot of brands make a wide version of their boards, which usually adds about a centimerter or more to the waist width giving you more room for your feet. If you are able to return your current board, I would definitely go this route. With size 9 boots you should have little to no over hang on your heels and toes since there are a number of boards wide enough to accomodate your feet.