Having babbled all that, if you don't notice anything wrong with your room, don't worry about it too much.
I have to agree. My room is okay now, but my last room was very unsymmetrical and the image showed it. Soundstage was weak and mobile. So a certain range was centered, but as the range moved (like a guitar chord change) the image moved. That was real noticeable to me on music, but not for movies. In my new, smaller room, I don't have that as much, but I have a 7 db spike in low bass (I'm guessing about 50hz) right behind my listening position. I also have some harshness in the highs at loud volumes that I think are reflective issues as the highs get bouncing around my small room. So I'm trying to tame with basic treatment before I go full bore or give up. I’m preparing to run REW, but don’t have all my ducks in a row yet. Not sure that will tell me much, but can’t hurt.
It generally sounds great, so i'm not going to over do it. ("Not going to over do it, not going to over do it." I have to keep saying that to myself!)
