The answer is it is possible to have speakers that are too large for your room but that's not your problem.

Place them along the length of the room instead of the width. Place the back 2 feet away from the front wall, space them 9 feet apart and sit 8 feet away on the diagonal. Treat the first reflection points on the sidewalls and floor at least - ceiling if practical.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated