Yep, I used 2 cups as well - eyeball it. It was probably a tad over, but I do fill the tub to the top. I had another wonderful bath last night and fell asleep in the tub! Note... we're talking 3 am here... working from home means sometimes pulling all-nighters.
I added a few drops of either lavendar or rosemary oil, can't remember. Linen water on the shower curtain is great too (and CHEAP at craft stores). I did my enema right before bath (good time to let the bath water cool a bit, fyi) so this process was over an hour and well worth every minute.