correct.. the room is about 14.5 feet from the front wall to the back, and the alcove takes up maybe 1/3 of the back wall going back another 3.5 feet (tucked under a flight of stairs that basically run "behind" and parallel to the back wall. Equipment and storage racks are tucked under there.
Seating is approximately 10.5 to 11 feet back from the front wall.
Having a small room seriously constrains both sub placement and seating positions. I tried to follow some basic guidelines, (not placing seating in the middle of the room, and trying to avoid making any two dimensions multiples of each other.. I know length and height are close)