Oh that is a hard question because there are two camps of thought on it. Personally, I feel IM is french sizing, not IT. Although there are websites that list it as IT sizing I think they are not correct. IM sizing is really all over the place lol.
I own all my beketts and Willows in size 38. I am a US size 6.5-7. So I ordered using french sizing recommendations. They fit me fine. But I could probably size down to a 37 and wear no socks or a very thin nylon sock. It would be tight across the toes but eventually loosen up a bit. But I choose to order sz 38 because I prefer not to chance it. Plus, they fit great and I can wear them with socks, which I prefer. Days my feet feel swollen, we all have those days, I am glad I have my Willows and Beketts in 38.
My Bobbys I own in sz 37. There is less padding so they feel perfect in this size.
All my other IM shoes: sandals and dickers and slouchy boots I also own in 37.
I don't want to recommend the wrong size for you! Hopefully my experience above will help you?
If you can, try to find a place that allows returns. Hopefully those who are the same size as you will chime in.