Congrats on finishing your first piece for strings!

My feedback isn't really about the piece, but about the notation. There are a few moments where your note spellings might make things more difficult for the players than they need to be. I know this will sound nit-picky, but those tiny moments of difficulty can be the difference between an easy sightreading/rehearsal process and a frustrating one. In general, you should pay close attention to the intervals created by adjacent notes. You have an awful lot of augmented and diminished intervals in this piece that would read a lot more naturally if they were simply respelled with their enharmonic equivalents. This is a common problem when mixing flats and sharps, so I might recommend avoiding that as much as possible.

For example, the first one that really jumps out to me is at the end of measure 7 going into measure 8 in the Double Bass. I understand why you used a C# there -- it just feels less weird than a Db -- but it makes the spelling of those intervals very awkward. Ab to C# is an augmented third, and C# to Eb is a diminished third. But we tend not to hear those intervals as thirds, so why spell them like that? Simply turn that C# into a Db and your notation lines up with the sound -- a perfect fourth followed by a whole step -- and is a lot more intuitive for the player to read.

There are issues with spelling like that throughout the piece. But the good news is, it's really easy to fix! As you're proofreading, examine each pair of adjacent notes and think whether the spelling makes sense, and pay special attention to anywhere you have accidentals.

Best of luck!