First off, I absolutely LOVE the theme you have. It's a beautiful and very charming melody! You have that late classical/early romantic flair and it's expressed beautifully. I rather enjoyed listening to it.
As for criticism:
1. Since the horns and clarinets are transposed, their parts should have different key signatures. This is for the sake of proper scoring.
2. While I love the melody, I do think that it's repeated a bit much. I think that at measure 28, after the strings and other instruments have had the melody, you could move on to a variation or development of the theme and build off of that. The reason is because, since you have such a charming melody, you wouldn't want the listener to hear it too much and get tired of it. You'd want to present it just enough, so that it's that much more satisfying when you bring it back. You added some nice variation when you altered the melody after the repeat, but I wouldn't advise reusing the same melody for an entirely different section. It just keeps the piece from being stagnant.
Overall, I think that this is a wonderful piece with a brilliant melody and harmony! I think you can expand on it. 😄
Great work!