hey Amon, I think your size (43) works the same as ours (the netherlands).
My Caboots, also shoe size 43 were 9 or 9,5... I'm not exactly sure, but just typ it in on google and it'll roll out.
just something with uh.. "shoe sizes converted" I don't know... just try something, that's how I found myn.. fit perfectly by the way, and it's like walking on air...