Contact Burton or the shop where you bought them, you will need mediums just like me. If you can get them to send you some medium bindings see if you can hang onto the large toe caps.
The medium binding will automatically have your binding more centered because the base plate is significantly shorter.
Your boots will fit snugly but well. I am really enjoying my mediums but I have the large toe caps on there as the medium toe caps didn't work (hurt my toes).
As I said in my thread lots of people are having this issue and I think Burton should stress the need to try on bindings for people in the middle of the two sizes. They can put a note on their size charts and tell their reps and shops so people have a heads up.
It seems to be mostly people who already own Burton bindings who are getting caught out because if your old burton bindings fit with the same boots/ board who would think the new ones wouldn't.
Its the reflex feature that forced them to reduce the adjustability. It is a good feature though and I noticed more pop.