Schumann Op.68 No. 28 Remembrance

[quaver]

Here I am again needing guidance and help with chord progressions.  I am trying to teach myself and so far seem to be handling it quite well.  Measure 8  with B# in the bass has me puzzled or could this be a chromatic step up to C#.  Also measures 20 and 21 pose a challenge.  I do not know what chords belong at these two measures.  So many accidentals floating around.  Your help would be much appreciated.