Neat take on the classical dragon design, I like the description, how you experimented with a variety of sources for composing this!
Just some, eh I say, ramblings. I just do similar stuff, actually for some sci-fi ideas, and of course for the huge flying beast, I rather use the four limb form. When considering the six limb anatomy (that's not something impossible if one doesn't assume strict Earth biology as base) the placement of the "engine" is the problem, those massive flight muscles. This creature seems to be aerodynamically sound with the wing surface and balance, however the proportion of wing muscle mass is just too small.
I mean even if I assumed much stronger muscles for an unit of weight than terrestrial animals have, this feels off to me, as then the tail and probably even the hind legs would feel vastly overpowered. Of course the classical six limb western dragon is often portrayed like that, with a massive and heavy hindpart. Slender designs which look dragon enough are more or less possible I think.
Actually pterosaurs carry some hints towards a potentially more dragon-like creature, I mean those ridiculous ornaments. If the creature had a tail with a somewhat similar wing aspect ratio to a typical large pterosaur, it needs to have a lot of mass of anything on the front to have good balance. An elegant powerful dragon head and neck could also do the job.
Anyway, the construction is nice and is an interesting unique design with all the details thrown in!