Hey, I really loved the feel in this piece, really beautiful and sad. I just noticed a couple things which caught me out a bit. When you change to the Fdim chord, sometimes it clashes with the previous chord (B flat major) because the B of the Fdim chord has come in early while the B flat major chord is still being held. You can hear this at 1:23 . Another point is that I found it difficult to follow a particular melody through the piece because their seemed to be a few different melodies happening in the strings at the same time, aswell as no repeteing motif that I could grasp onto. I think if you have some well defined melodies that come in and out of the piece that the listener can recognise then it would make this piece even better.
Overall it felt like it would fit well into the book 🙂 Well done.