3 years and still wondering/looking.  

I think its John Mascheroni. I used to have a sofa with those same back cushions that overlap the seat cushions. It was labeled. I might have a picture somewhere.

Hi Juanearl,
Thanks for your great insight. I did search for John Mascheroni and I did see some similar design traits. No luck finding a good match however. If by chance you find that photo, I would love to see it, Meanwhile I'll continue my search.
Thanks again,
DjL

I like the way you have placed your coffee table (not squared with the sectional). I do.
Aunt Mark

The way the tight back overlaps the seat cushion is a very distinctive design feature but I don't think there's a standard term that describes this kind of thing. I am pretty familiar with upholstery terminology and I've never heard of one, anyway.
I did a Google image search for Ligne Roset sectionals and found their Fugue sofa that has arms like that, and maybe the back too---but the only examples of any Ligne Roset sectional were all of two long sofas butted together, none with shorter sections so that an armless one could be on the end. And the Fugue always has legs, never the upholstered base. No other Ligne Roset sectional comes close.
You might find a label under the dust cover on the bottom if you want to pull that off. It is easily replaced and won't affect the value if it's not original.
It's kind of odd that there are no labels---unless it has been reupholstered.

Hi Spanky,
Thanks for you help regarding the quest to identify my sofa.
I spent a lot of time this weekend looking at the Fugue line from Ligne Roset and as you pointed out, the style of the arms are very close. I had never seen the Fugue sofa. It's a good looking line.
I did look under the dust cover and found nothing but a few cobwebs. I could not tell weather or not it's been reupholstered, It looks original to my novice eyes.
Thanks so much for your comments and suggestions. The search will continue.

Hi Aunt Mark,
Thanks for your comment on my coffee table. I do like some thing askew but this table is square with the sectional. It is a Paul Kjaerholm knockoff that has the appearance just like you have pointed out.