barista,
It is possible you just absorbed the coffee, sometimes this happens. I am curious as to why you are lying on your right side instead of the left side? The left side is best if you are trying to cleanse the liver. Did you do any stomach massage while you were on the toilet? Sometimes this helps move things along. I would not worry about it too much though. Try the left side next time and see if things are different.
Also you don't need to get the coffee solution that far into the colon, you only need it to be in the Sigmoid colon for best results. IMO 18" is a long way up. Check out the enema & Bowel Cleanse pages here on curezone for more in depth info on coffee enemas //www.curezone.org/cleanse/enema/