I'm really enjoying your piece :)
While I would agree with Monarcheon that it may not be a true "solo piano" piece, I'm not sure that's what you were going for. That's how it seems as I listen anyhow. It's introspective, and the subtle pushing and pulling communicates to me the emotion you were going for. I actually liked your violin throughout the whole work, including the last few bars. The same goes for your ending notes--true, it's not the tonic like we would expect, but with the right set up in advance you could end like that quite nicely. I think what made them feel unexpected or incomplete is that you didn't "lead" the audience to be ready for that finish. Unfortunately I'm not sure how I'd make that happen, but the challenge of making something unusual work is exciting!
Your construction is good, your techniques are good, don't be afraid now to look deep into the music as you're writing to find the "hidden gems". Then your work becomes showing that stuff off. It could be as simple as a single chord substitution to set off a melodic phrase, or something radically new that nobody's dreamed of yet. Go big, and enjoy it! Composition is a big world, have fun in it :)
Keep composing!
Gustav Johnson