For anyone who is interested in how to achieve the reserved, deep tone:
1) octaves in the LH bass should be understood as the upper note is the double, not the bass. Thus, the bass note should be louder, the upper much softer. This produces a deep tone necessary to express the anguished character.
2) middle chords needs to be voiced similarly to the octaves to achieve the reserved tone. For example, on beat 2 of the first measure, playing the upper note major 3rd softly and making the 6th more pronounced sounds deeper. And on beat 4, making the open 5th more pronounced has an empty quality that helps enhance this character. This principle of carefully coloring the tone of these chords is what you can do to achieve an anguished, almost sobbing, tone.
3) the melody is not to be played softly, but moderately loud, but not so loud as to be shouting (though there are places where this interpretation may be acceptable to enhance that anguish.) The melody is not to be understood as pure legato, as in a singing manner as with many of the other nocturnes, but it should be understood as expressing anguish. As such, it should be performed slightly percussively and mostly non-legato.
Performed it this manner, the character of this piece, one of sadness and anguish, will be expressed clearly. Any other interpretation, is simply wrong.