Hi realpiano,
This "Prelude No. 7" is one of the most difficult pieces in the entire piano literature. It's difficulty lies in its very simplicity, leaving the pianist no place to hide. The great Chopin interpreter Moritz Rosenthal once said, quite late in his life, that he had been studying this prelude for decades and was still gaining new insights!
I like the way you achieve the dolce sound. It's very sweet and gentle indeed. Here are some suggestions:
At the first note of the piece, the E leads up to C#. It looks straightforward... but it's not. We call this a "soprano pause". You see, the piano's function is to emulate the human voice in song. In the Romantic repertoire in particular, there is great emphasis on playing cantilena or bel canto melodic lines, as found in this prelude, in a flowing legato way, as if the piece is actually being sung. If you accompany singers, one of the things you quickly notice is that unlike the pianist who puts a thumb on the E then immediately puts the fourth finger on the C#, a singer is unable to do that with the voice. For any leap like that, the voice has to be prepared. In doing so, there is a very subtle delay, known the soprano's pause. So you need to incorporate that element into your playing in this spot. It happens again in measures 8-9 and and requires that same subtle pause between the A and high A in the RH.
In all of the double notes and chords in the right hand, always remember that the soprano voice is in the top notes forming the melodic line. So you must always voice those to be predominant over the accompanying notes underlying them, as they are less important.
In the 8th full measure where the C# octave is in the RH followed by the E, you can put a subtle break in between the the octave and following note. That's a spot where the singer will regroup, so requires a slight pause for a breath. You should literally take a breath there too.
In full measure 12, a couple of things: 1) I'm not hearing the F# harmonic chord in the left hand; and 2) in the double notes following, the lower one is A#, not A. The wrong note is just a read error, but jarring to the ears.
Measures 13 and 14 are interesting. In the RH notice that the bottoms of those double notes form a descending scale as accompaniment within the same hand. Scales in compositions take on significance to the ear. It's not so important as to drown out the upper notes, but still it needs to be heard harmonically, so feel free to bring it out a little more.
In measure 15 as you approach the 16th double notes in the RH, you can broaden (slow) the tempo just a tad so that the 16ths are blended in and not overly emphasized.
It's best to take the very last chord in its own pedal. Use sychonized pedal there--don't play the pedal with the chord, rather play the chord and then catch it in the pedal.
I hope this is helpful to you.
Topic: Chopin Prelude Op 28 No 7