Your layout means the surrounds work for one seat and then too is sub-optimal. Further, it creates issues for everyone not in that seat. If that is acceptable, the locations I mentioned earlier will work.
My L/R surround speaker positions are not perfect either... but I think TV/movies sound better with them than without them.
Your sofa looks big enough you could unload a bus onto it. I think you have to ask yourself a couple questions.
1) How badly do YOU want the surround experience for TV/movies?
2) How interested are other regular watchers, (wife, kids), in audio and particularly surround?
3) Where do you usually/always sit?
Since you came to a forum, made a diagram, learned how to attach it, learned how to attach a picture, and asked the question, I'm guessing you're pretty motivated to optimize your audio.
If other regular watchers are audiophiles, you may need to reconsider your furniture. In any event, you cannot seat 10 people in that size room and have perfect audio for everybody.
If you are the only audiophile, I would say to
optimize the system for your seat, and do your best to
accomodate the other seats.
You have already made a concession w/ the soundbar instead of separates. You may have to make some more.