Hi Vivian!
After listening to the song, I noticed it does have a very adult theme for such a light-hearted show as Cinderella. If you think it does relate to you that much, try looking at the song from a lighter point of view, as to not make your director uncomfortable. On the other hand, if you want to find a new song that fits the vocal range of Could I l Leave You, I would go with "Adelaide's Lament" from Guys and Dolls, or "Wait" from Sweeney Todd.
While typing this I noticed it's been a long time since you posted this, so I hope it's not too late! Break a leg! :)
Nolan
Nolan Rice