Is Tree #5 turning into a UFO?

At what point does a work-in-progress become a UFO?  I started Tree #5 with great eagerness, but it has been languishing on the design wall lately.  To me, a project becomes a UFO when I start to dread it, rather than feeling excited about it. So I'm trying to recapture my excitement for this project!
My plan for this quilt is to use more detail to make it resemble an actual sycamore, rather than just a generic tree.  I'm challenging myself to work with a range of 5 values, rather than 3 as I have in previous quilts.
Here's an inspiration photo I took of a sycamore.

Here's the quilt so far.  It's kind of hard to tell what it will look like, because there are lots of big white gaps in it still. I will be filling the gaps in with a second color, just like a sycamore has both gray and white bark.  I haven't decided on the second color yet, but I'm considering green. I just need to make sure that there is enough contrast between the blue and green to show up.

Here's a close-up:

 

The Columbus Modern quilt guild is hosting a UFO challenge and I'm hopingit will motivate me to get this project done!