I actually failed my composition class.... so my opinion can't really be taken that seriously, I'm afraid.... but I think the theme already sounds a bit more like a variation on a theme, than an actual theme itself. Perhaps the initial theme could or should be more simple in terms of the harmony?
Then you could save the more complex re-harmonization idea for a later variation?
I think it would be hard to make variations on what you've got, as it already contains so much harmonic development.
I've never been very good with theme and variations myself. Not that that should stop you
Some beautiful harmonies!
Topic: Original Theme for Variations