Let's go for a 1000 population for Winterhaven.
For the Inn, the staff and their immediate families live there, It's a large-ish Inn that sees movement, so let's say 8 people live and work there.
For buildings 4, 5, 7 and 8 have a family of (averaging) 4 living there. That's 18 people.
Valthurn probably has a couple of servants living there to do the menial work (maube even under apprenticeship). That's 3 people in building 6.
The Temple (area 10) probably has about 6 people living there, between clergy and lay servants. We're up to 35 residents, now.
The Manor (area 14) has spelled out 11 residents. 46 so far.
The Barracks (area 13) house 10 guards. 56.
That leaves us the Tenements (building 9) and the "H" homes. These are probably 2-storied buildings. The homes can fit 6-8 people before getting too crowded. Assuming 6, that's another 36 people. 92 so far.
The Tenements can hold another 60 people in 12 separate units.
That brings the population of Winterhaven proper to 152. We can round that down to 150.
This assumes the buildings are mostly two-storied. The tower is five-storied and is called out as the tallest building in town, so there's no reason why several buildings can't be three- or four-stories affairs.
That leaves us 850 people living in farmsteads outside the walls. Assuming an average of 8 people per farmstead, that's about 106 farms spread around Winterhaven.
Compare that number to the medieval village of Autoire, in France:
Even in modern days, when people don't live as packed, it boasts 312 people in 7 square kilometers (about 4 square miles, or a square 2 miles on the side). That area reaches the borders of the Lair and the Burial Site, if perfectly square. If shaped like an oblong, it can be stretched from west of Winterhaven to the east, alongside the King's Road, with some towards the south, closer to the Burial Site.
In fact, I'll be using Autoire as the look for Winterhaven's buildings:
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