20 - 30 miles for a city is huge in medieval terms, Aval, but as always there may be in-game reasons for this. I'm a big fan of exaggerating city sizes anyway, even if it does put them out of scale. For me if the map looks artistic then I'm quite happy to take liberties with scale. Although bear in mind the larger you make the cities the 'smaller' the land area looks to the eye. One of the best ways of helping the eye to denote scale to show that the map is of a large landmass is to put in a ton of city and town labels.
150m sheep? Is this an alternate New Zealand?