the toe plates are already adjusted to the shortest distance on an M sized binding and there is only 1cm of overhang. i suppose thats too little?
pictures would help.
That said if you are using burton boots in a burton binding the 7.5's should fit the size small. In my earlier advice I said get the medium, you should only do this if it's the case that when the boot is properly on your foot and the straps are at max length you don't have enough length.