First of all, amazing art!
I think the issue might be that the wings are too small and some of the digits are too short. I looked up real bat wings, and they tend to span most of the body of the bat, and the "fingers" all come to about the same length, whereas the ones you have drawn seem to "cascade" down, each digit longer than the last. And although her wings are depicted as close to the body, there aren't any wrinkles or overlapping of the membrane present, which makes each section of membrane/digit look like they aren't connected to one another.
I think if you want to keep the tiny cute wings, they'd work better if they were cartoony. But your style is pretty realistic, so you'd have to play with it to achieve the right balance. I guess it all comes down to your intent for the pose and how realistic you want it to be.
I found
an illustrated guide on DeviantArt, but looking up photos of bats' wings should also help to get the proportions right.