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.
Chomps, let me know if you go this route but for some reason can't keep the large capstrap. I have a brand new set of the gettagrip capstraps that I may be willing to part with. I have them only as a backup so I don't necessarily need them. Plus we wouldn't have to fuck with shipping since I'm in Lansing. Just a thought in the event that you can't keep yours.