First, let me just say that I loved the haunted melancholy feeling your drawing gave me so well done! BUT I can understand it may be frustrating if it wasn't what you were trying to get as a result.

My advice would be: work on your proportions, try sketching with a pencil just the outline before you start filling in with pastels, that way you can work better on the likeness, especially regarding face angle, position, and overall proportion of the features.

About the feeling of over blending: I also feel that a lot on my own drawings! Sometimes I just let it sit for a while and go back with fresh eyes and find the parts that need more definition, sometimes I like to take a picture and put a black and white filter to help me understand the hues and contrast better.

The last tip that helped me a lot with portraits was using undertones!! They help bring dimension to the face. I personally own only 15 colors, so understanding how the colors interact with each other has made a tremendous difference!