It's not bad, but also a bit boring. I can hear your construction, which is a bit fugue-like, and that gives the music a distinct unromantic feel. But the theme(s) is too flat to carry the several minutes of music all by itself; Baroque themes tend to be more, well, baroque, and the piece is also not very dynamic. That makes it, in my ears at least, just too repetitive. More dynamics and a bit more rubato might solve that, but it's not easy to add more dynamics to sampled brass instruments and keep them sound realistic. Another option is to superpose a short, slow, different melody on top of the texture of low brass from time to time.
Anyway, those are just my thoughts. I'm curious how your teacher(s) evaluated it.
The 1st measures sounded like the NEW WORLD Symphony...
The contrast between the slow & faster movement didn't seem to work.
From the flowing, chordal section to the tuba solo was like switching from a serious movie to a farce. Maybe a less jazz-like rhythm for the tuba could allow for a smoother transition.
Two movements don't have to contrast in speed.
The ensemble had nice balance.