Did you ever come back to this?
The bones of this track seem promising to me, just waiting for some extra flesh to bring them to life.
Some thoughts as to what:
Perhaps sounds of lapping and rippling water could be incorporated in somewhere? Small echoing drips, maybe?
Or if you wanted to take it in an entirely different direction, it could be brought outside to storm and rain, perhaps crickets...
The rhythmic tapping that comes in from time to time, what if there were more versions of that with sounds of something else tapping? What if in one or two places it echoed?
This seems like a theme you could do a lot of interesting with looping back on itself in layers, fugue-like.
I suspect keeping the melodies simple and all in this soft piano is a big part of the mood, and would be well preserved, but perhaps having some subtle hazy tonal drone fade in and out underneath it like you might hear in a horror game soundtrack, could help flesh it out without competing at all for the melody lines, such as they are.
You wouldn't want to make it crowded, of course, but somewhat less barren, this could get really interesting.
Hope this enthusiasm and advice has not been unwelcome, anyway.
Good day!