In designing bedroom spaces main focus is, of course, placement of bed. In my opinion, bed shouldn't be positioned under windows for many reasons, mainly because of draft, cold and wrong type of illumination. For those reasons bed is placed at wall that faces neighbours. That wall is also soundproofed and insulated, with wooden finishing - clapboards, or ordinary wooden planks at wooden subframe. Due to this change of space organization, wall with window does not have the need to be insulated, and the loss of space is reduced to minimum.
Finishing of the other three walls is paint according to proposed colour scheme. Colours are bright and modern to emphasize modern country style. Wall with window should be most intense in colour, I have provided two solutions, first very vivid and striking, and second a bit moderate, according to your liking.
Furniture should be restored with new paint and accents like described.