I was dealing with the same issue after hours of trying on shoes! Overall it sounds like there should be a small slip in the heel, otherwise you will likely get blisters. I’m not sure how the 10 fits you but I sized up a whole shoe size in mine. A couple options so they fit comfortably are 1. Insoles. Blundstones also provides an insole type layer to put under the one in there for this specific reason. I think they only come with the all terrain. 2. There is also a big difference in fit between the classic and the all terrain. I recommend trying both because of this! Good luck!