Very nice! I hope that the melody in the beginning will be played by 2 Clarinets soli because there's very scarce room to breathe and if they were both playing they could each take breaths at different places (much like the voices too). Are the cellos being doubled by contrabasses in this? In the classical era composers would write only one part in bass clef that was meant to be doubled by both cellos and contrabasses. I think if it's not being doubled, a contrabass part would certainly add some body to your orchestration! I like how you vary the reprise of the introductory material by thickening the texture and adding nice contrapuntal lines in the basses. The contrasting section, while related to the original melody is different enough to inspire interest. The B section also has almost a sort of Christmas Carol type of character to it! The C section, being more melancholy and quiet gives the listener a break from the more joyful B section. Actually now that I hear the A theme again it sounds like a Christmas Carol too! Thanks for sharing!
If you want some great orchestration tips and tricks check out this channel: https://www.youtube.com/@thesecretsoforchestration. There are many concepts/terms in this study of orchestration which I haven't heard used anywhere else, such as the "device" which is the combination of instruments playing the melody, while the "texture" is the combination of instruments playing the accompaniment either underlaying, interlaying or overlaying the material in relation to the melody. Check it out!