while to overall proportion and placement of doors and windows is great,
to my eye your station will look more american if you
change the windows (if this isnt too much of a pain) to something more rectangular and not square- (longer vertically) and say 6-8 window panes -if this is too much -consider adding a bay window with its own angled roof for one of the windows on the track side
change the chimney-offset to one side a bit, and make it a bit taller-and even the style-the little ledge you have seems very English, Irish etc-but could possibly be the same in the eastern US
shingles ? depending on locale you wish,
and corbels in a US style -
even wainscoating?? or vertical strips to make it look like board and batten construction
colors are fine-green and white were used
as were red and white, yellow and brown etc
also i might suggest the use of US ads, to also add to the impression
other details might include a station lamp or 2 in US style, as well as benchs, a coke or cigarette mahcine, gumball machine etc
whats the diameter of the tank ,did you use drawings 
.split again ,imay leave it now until i come back from the states,could be even longer getting opp on leg 1 st march a well we will have it sorted soon