NAC can help but there are many things in the methylation cycle including methionine, taurine and most of the b vitamins. There are a number of testing facilities and educational material online. I am thinking Dr. Amy Yasko has some good information as well as Dr. Deth.
Traditional Chinese Medicine offers some good diagnostics (tongue and pulse diagnosis) as well as herbal formulas. Acupressure points can be used for liver stagnation.
Regarding the liver fluke issue, have you had any traditional testing for this, or go back and get retested?