That's a good thing y' got goin'. Vox up! Feature guits, up! verb down.
My nit is with some of your chord choices. There ain't a diminished ot half-diminished, augmented chord anywhere in it IIRC. The Fmaj7 [bVIImaj] is a real welcome changeup. I think you could use a little more non diatonic action. Like the chorus...rundown from the Cmaj7....B-7; then a change to , say a Bb6 followed by A+ and cycling back the the Cmaj7, would add song zest and zing...and , for the genre, it's kind of anticipated ....and the diatonic sameness is kind of a let down.
It's nice music...but it needs a little sonic danger, IMHO.
And some more slop and inventiveness , say in the piano comping....lines and rythmic surprises...... would do a lot: the music is so tightly structured that it tends to sterility.
Gino Vanelli's stuff from 1979&80 is prolly some of the best schooling for composing in this sort of scheme. Stock ballad fancy-feast. It could be really worthwhile to listen to some of his records...study the changes and substitutions....to get a handle on it. It'll bring your composition out of the Hamilton, Joe, Frank and Reynolds mold, and into much hipper territory!