You have grasped the overall effect of the piece, and your interpretation is quite enjoyable.
What would make this an even better performance is more attention to the top notes of chords. It is evident especially in the quiet sections that some of the top notes are of uneven strength from chord to chord. In some phrases you bring them out nicely but in others your melodic direction is sometimes ambiguous. I have noticed this usually occurs when you have interspersed bass notes then have a couple upper chords. I would suggest giving attention to the melodic line for these top notes.
I think the effect of unevenness you speak of is not primarily from the chords, but from the need to have a clearly stated melodic line. Additionally, what helps with more even note placement within chords is to not just plonk your hands down on the keys, but have a more fluid movement. An analogy would be the swing of a golf club (or any other racquet sport), in which the preparation and follow through for the swing are very important to the end result.
Agitato is quite nice, and well judged.
6th bar of double staff section - the second to last eighth seems rushed. Careful not to over anticipate going down to the bass of the next bar.
Last 2 bars - I know playing large chords very softly is a challenge. Another place where using more fluid movement in approaching these chords would help. Think of landing your fingers into the keys, and don't stop the motion when you hear the notes sound - keep the finger motion going and follow through with your approach. Also voicing the top notes in these types of soft endings is useful. If some notes don't sound (in a live situation), but the top note is voiced, an audience will still perceived it as a well-played chord.
Good work here.
Rachmaminov op. 3 no. 2