Mahesh,
I am also a learner of astrology.With my limited knowledge I can tell you the following-
Yes, you are right,Sade-sathi is 12,1,2 from Natal moon of the horoscope.
In you case, the first phase and 2nd phase could be a bit of problem.Especially the 2nd phase when Shani enters libra..there could be issues related to your siblings/house/health issues.
Basically, however benefic Shani is for the native, during Sade-sathi the peace of mind is never there.Good things will happen as well during Sade-sathi, but this period in your life changes the way you look at life.It is a learning lesson we should take and make ourselves stronger.
Thanks,
Ms Hope