I think you've already hit that it looks too "square" still. My first thought is that it looks like it's still divided into "sections" that use about the same cross section. See the colors on the image below as these sections. Also, the areas between sections are too tall - see the black circled areas in the picture.
Annotations on image:
However, you've already got the basic idea needed to fix this! That framing you have in the back, that's just a single block wide in the shape? That's the key. Put up that framing, then do each single block cross section individually. That will fix your colored sections. Then, for the tall steps between sections, don't fill in corners (do the analog of the right side A).
Then you got it! It already looks pretty good, but small change's'll help out.