How long have you been doing CEs? It took me five or six months to get the real decongestion feelings on both sides (while laying on my right)--especially after I increased to two CEs back to back. The flushing of the first increases the absorption of the second.
As for right vs left, I have read posts where diagrams are supplied but I still don't see the reasoning. I'm falling back on Dr. Gerson's decades of clinical practice. More adventurous types than I do get creative with enemas, but I continue to worry that left side is a colonic and can wash out flora.