Hello Tortualex
I really enjoyed this piece. The rhythm is rather unusual, and fits perfectly well with your motif and its variations. I recall that I have heard this rhythm before (but no idea when and where). Somehow, I got an association of early music (pre-baroque or renaissance, I don´t know). But it is certainly compelling.
A-minor (and A-major in the trio) is just the perfect key. The modulations are fine and I also experience some drama in some of the phrasings.
Occasionally, some of the harmonic transitions (like in ms 8 or 16) felt a bit odd. I would have used a more common practice half-cadenza transition. I would also have sculpted the dynamics a bit different. And here and there, the melody is a bit jumpy. But…. that´s just my personal opinion.
Otherwise, I think that the piece is coherently structured, including the nice recurring to the original motif.
There is only one more thing: I think that this piece is a wonderful platform for further development. To me, it is just begging for an additional set of free-standing variations.
Thanks for uploading this piece. It is a source of inspiration for me.