First of all, great job especially on start :) From what I see based on Proko critics, your lighter shadow is lighter than halftone. For me squinting eyes help and usually I do a little small diagram of 5 values by side of the drawing to have clear reference how dark should my dark be and how light the light :) using wide range od pencils helps too. Other than that, try to simplify even more :) If area in the light is the main focus of your drawing, then shadows needs to subdue a little to don't steel the viewers eye. Nonetheless, solid execution of a assignment! It is made to challenge you and help you grow :)