Wow, that's a fantastic piece! Thanks for sharing it with me. You should post a link to it on the Composing Group wall. That way you can get feedback from other composers and Paola, our lead artist. I'm not sure about the limitations of Note Flight (though I plan on learning more, so feel free to shoot me tips), but I suggest having the pedal chord diminuendo toward the end, or perhaps break away, one note at a time, as you approach the end, leaving you with one or two notes (i.e. I and V, I and III, or just I) in the last measure(s).
I'd also modulate or invert that pedal chord from time to time, particularly when the chords in the strings modulate from the key. That would add a little more suspense and aural relief.
I also noticed that, sometimes, the melody deviates from the typical 4/4 phrase of say 4 or 8 bars at a time. When that extra measure comes it, it sets the listener off of their "internal count", which can be jarring. If that's your intention, then it works, but if you want the listener to feel constantly afloat and "in" the piece, I'd avoid any standalone "off" measures, and just add another to keep the number of bars in a phrase even.
On a completely separate note, I've added your school to our list, so you can update that question and add a pic by clicking on Settings. Great to have you here. Thanks for jumping right in!
Hi Jia Jie. Cool name. How do you pronounce that? Welcome to Musical Exchange. Can you please let me know what school you're with. I see that you you've listed yourself as a student, but being with the DOE. Drop me a line, and we'll get your current. Thanks.