Three Pears Pencil Sketch

I thought I was finished with this pencil sketch until a brilliant artist/friend of mine suggested I "up" the contrast a bit.  The more I look at my sketch the more it appears to...not stand out as much as I thought.  The pears are not popping out of the paper.  I'm seeing a pattern here.  This appears to be the same problem I'm having with my paintings.  Not enough contrast.  Not enough "ooompf".

I need to dig out my "soft" pencils or the "B" range and redo parts of my sketch.

I just hope I don't overwork the sketch.  I suppose the worst case scenario...I get to do another one.  Just means more sketching/drawing time for me.  Sweet!