hello Matthew
i can't but disagree with your prof
what i think is you do have to concentrate, but on developing further on (musically), rather than on the first two pages
i think you have quite some ideas and maybe prefer to drift from one to another rather that picking two or three to form a single-styled piece. i think this is great, i'm sure your continuous search will lead you to a more closed form, without losing the potential for various ideas.
the first theme is lovely.
i like your balance between expected and unexpected harmonies in measures 13..23 (and later on, too).
starting from measure 36 you seem to either become minimalistic on purpose (which i have neither enjoyed nor understood), or maybe lack some techniques that will come with experience.
the slow part at 67 sounds very appropriate.
and sorry, i can't bear that ending, it's completely out of the mood, at least to me.
i wish you returned to where you started from (as i often do myself). the first theme is so soft and beautiful that one feels disappointed not to hear it again anywhere in the piece. just a thought.
overall, very lovely and promising piece. keep up the good work