Just a couple of thoughts.
One of my feet,like most people,is larger than the other.My normal shoe/boot size is 10 but if I buy those my right foot is a tight fit.So over the years I always but one size bigger(11s) and with Bike boots this means I can wear thick bike socks to pad them out and stack inside with those cheap foam inner soles.
This makes them a firm fit and comfortable.
Also and old trick to soften new shoe leather and make a better fit is to wear the shoe/boot and gently warm them with a Hairdryer and work some Saddle soap into the leather as a softener.
HTH
