Sorry I didn't respond quickly, I read your post but I kept forgetting to reply.
Anyway, I tried adding the hair pins under the two note motive and you were right. It sounded much better.
To answer your question, I was originally going to make a transition from this directly into a faster B section, but I've since realized that two ternary forms surrounding an Allegro middle section was closer to what I actually wanted, so the first upload is most of the A section for the first ternary bit, I suppose.
I've also composed some of the B section. I'm entirely not sure about some of the double stops, and I don't have a transition from the A section written yet.
String trio Adagio Cantabile Theme 2-2.mp3
String trio Adagio Cantabile Theme 2-2.pdf