Got it. 26.7 is more typically a size 9 US
At 12/12 you can lose more width again, so you will be comfortable on boards that are 25 to 26 at the inserts (not the waist which will vary greatly depending on the board (more on that at: Wiredsport | Snowboard Fit Tips Part One
You will love the Goliath 156. Let me know once you have had a chance to ride one.