So I am practicing the first movement of the Pathetique Sonata. There are some things I find tricky about it(like a septuplet that comes right before the chromatic scale) but perhaps the trickiest of all of them is the sudden dynamic changes and in general quiet dynamics in the left hand. I find the left hand difficult when it comes to quiet dynamics on my upright piano without using the soft pedal. Right hand becomes difficult with pianissimo, left hand is difficult with piano.
Here is my typical dynamic technique for the right hand. I press the keys with my fingers only when I play mezzo piano or quieter and I move my fingers more gently the quieter the dynamic is. My wrist only moves a little bit as I go from 1 finger to the next. The higher up the note, the less it takes to play it quiet and the more it takes to play it forte. If I am playing mezzo forte, I move my wrist more and if I am playing forte or louder, I use more of my arm muscles(especially in octave passages where it is really necessary). Its a bit different with octaves but this is generally what I do. With my right hand, if I try to play piannisimo, I usually get piano or nothing unless I am pretty high up.
With the left hand, I don't really have to use much of my arm muscles at all for forte. So if I play in the great octave(where most of the dynamic difficulty for my left hand lies), I can play forte notes the same way I would play mezzo piano notes in the right hand. But piano, very hard. I minimize wrist movement and try to play piano and what do I get usually? Either mezzo piano or nothing with very few piano notes.
So both hands have a dynamic limit just using the technique that comes natural to me for dynamics. This leads to me having to use the soft pedal for pianissimo which obviously is not ideal on an upright because the soft pedal on an upright does not decrease the number of strings hit by the hammer and thus this can lead to a dependence on the soft pedal for quiet dynamics.
Now what makes it trickier in the Pathetique sonata is that there are a lot of sudden changes from piano to forte and vice versa in both hands. Forte is easy, piano is hard for my left hand.
So if I can't get very many piano notes in the left hand using what works for my right hand playing piano, how can I make piano dynamics easier for the left hand and pianissimo easier for both hands without using the soft pedal or buying a grand piano(don't have the room or the money for a grand piano)?