Wow, very nice drawing...
Nice handling of watercolor wash.
Your rendering of form just sucks though.
- The hand is just too small. Put your own hand up to your face with the bottom of your palm on your chin. Your middle finger will tap just above your eyebrows. If you do that with the measurements in your drawing, you will see the hand is too small. Take the length of her hand and put it up to her face. The hand you drew is not foreshortened, so it should be as big as most of her face.
- The rectangle in the upper left does not help your image, and could be removed. Same with the ocean waves at her feet.
- Your light source is ambiguous, so your shadows are kind of random. And you lose track of your hard and soft edges on your shadows. That is not such a big deal in this kind of a watercolor, but it would be interesting to see you render this again with a strong light coming from one side or the other.
- To answer your question, no you didn't put too much detail in the face. I do think more carefully thought out shading would model the form better though. As it is, you are relying on your drawing, and ignoring the form rendering.
- Your green background is very intense color. Graying it back with a red wash would make it recede into the background more, and hence it would flatten the figure less. Intense colors come FORWARD. Gray colors RECEDE BACKWARD. So you don't ever want intense background colors.
- You have hard sharp edges on your round forms. (shoulders, legs, face) Sharp edges flatten form, soft edges make forms appear more round. Google "atmospheric perspective" and read up on the rules about this. You draw too well to not understand these concepts, so please do learn it. It will help your modeling of form a LOT.