E.A.
1) I also experienced decreased milk supply and was absolutely determined to breastfeed for the first 12 months. I actually did the ordering without a rx, too. Got Domperidon from someplace far, far away... Mine aren't blister packs, tho. Mine are just packages and are the regular Dom, under name Moridon. That may be the M your'e seeing on yours.
They've worked really well and I've used them with both of my babies (still nursing #2 at 8 months old now).
2) With 1st child - I simply stopped taking the pills once she was 12-months old. There didn't seem to be any side effects from stopping cold turkey. I still nursed her at night for a few months because that was our quiet/bonding time. My milk supply got pretty low, but made weaning that much easier since she wasn't really getting much from me.
3) Each time I've started using the pills (10mg pills, 3 pills at a time, 3x each day) I noticed dramatic results within about 2 days (or faster).
Hope this helps. If you're interested, we can compare our online resources/prices.