Good luck with your taper, JessieRose! I , also, notice water retention when I am tapering down from pred. I am on a low dose of pred right now, too, and my rheumy wants me to try to taper off completely. I have not had much luck with this, however, because I immediately experience increased joint pain and increased inflammation as soon as I go below 7 or 8 mg.
Good luck, also, with cellcept. I have read many great stories from members here who have done well on cellcept. I pray this works for you, too!
Lupus and RA and LOTS of Medications!