Julie,
First of all try and make your audio files into mp3 ones instead of m4a.. I can playback them fine, but maybe a few won't be able to so... better be "safe than sorry".
Now, on the work itself first of all.
I think it's a nice little "doodle" (meaning nothing bad with this work). It's got a nice round form that works well (A-A-B-A') and then it ends. It's quick and right to the point.
There are a few things that seem to be mostly instinctive rather than thought out, but due to your lack of experience your instinct is not working at its full capacity. Some things (especially the "B" theme) is not "square" enough. Usually music moves in 4,8,16 etc. In this case this is broken, or at least sounds broken, which feels weird, right after the nice "A" theme.
On the score now, here's a few pointers, to help you going:
a. You ARE allowed to change clef in any of the staves. You could have two tremble clefs, or two bass clefts, for all the pianists care. How else can you have music played high with both hands?
b. And you ARE allowed to change clef in the middle of a bar.
So the very first few bars, in the LH (left hand) should be notated in the tremble clef. All the notes of the D major chord are above the middle C, so there's no reason to keep it at the bass clef.
Same goes for that 16th run, which goes WAY up. Just change clef and you;re done!
c. You do not have to notate every pedal instruction, especially if it's 'traditionally' in every bar. Playback WILL be affected, but any pianist will know how to use pedalling in this case.
d. You do not have to put the same tempo marking more than once, if nothing's changed. Apart the one in bar 1, the rest need to be deleted.
e. Once you change clef in the bass, you will be able to center the dynamics
f. Add articulations and slurs. You play things in a legato mode mostly, so show the pianist how to phrase things and what to play legato and what not!
That's about all the general comments I can give, without actually proof reading your score...
Hope they will be of aid!