with Sidi go up a size, and go mega wide unless you have lady feet
That. They do seem to size quite tight. I would go to a shop to buy something like that though as shoe sizing is so personal. I would even try a couple of pairs of the same size on if the shop would allow it to check for differences
Just to throw a spanner in the works I am the same size in shimano and sidi I have narrow ladies feet apparently and swim in most other cycling shoes. It might be worth going to a shop and paying the extra.