Trying to figure it out without shooting photo references is not going to be very effective–you’ll often just run around in circles. There is a reason why professional artists rely on photo references–it is the only way to achieve accuracy in anatomy/figure, as well as natural looking poses. Even artists doing stylized works (such as animators at Disney) consult photo references, video references, and real life in order to achieve high level of expressiveness. Everyone’s got a camera these days–including the one on your cell phone, so use it and shoot references. You can even use yourself as the model and shoot in front of a mirror if you don’t have anyone to model for you.
Her line-of-sight looks awkward (staring up at something). She should be looking at the viewer or maybe off the the side. Also, her eyes look vacant because you are depicting her irises as if they are just flat discs. They should be reflective and they are actually conforming to the spherical form of her eyeballs, and they are also translucent. The lighting looks confused too, with different areas contradicting each other in terms of where the light source(s) is. Establish your light source(s) and then be consistent about it, otherwise everything will look incoherent and disjointed.