Hi, I'm a violist. This is actually a nice solo piece for viola, great job! (We don't have much in the repertoire.)
I played through it before I commented. My only complaint is the L.H. pizz passage (m. 25-30). It's hard enough to play a L.H. pizz on one string, let alone 3, all while sustaining notes on the A string. It's playable, yes, but you're asking quite a lot from the left hand there. The physics of playing the viola—a story for another day—can present a challenge when more than one note is required in a piece of music. Simultaneously bowing a note on the A string and plucking a note on the C string will probably only sound even close to sufficiently good if played by violists with larger-than-average hands.
If it were me, I would rewrite that passage altogether. From a stylistic standpoint, I don't feel that it fits in well, anyway.