Wow, Rina, you're a really good artist.
And, if you don't mind me pointing something out, I think I know why the 'extra' joint makes your wings look better.
If you look at the structure of a bird's (or bat's) wings, they're really modified arms. That so-called extra joint on your wings is the elbow joint. It looks right because those wings would actually work, anatomically speaking. Not getting into aerodynamics, cuz that's not my field. I'm just a med student dropout. xD