If you're in the US, you might consider working with a doc on this and getting a prescription. Using GoodRx.com, I got the Naltrexone for under $40 per 30 pills. I used a different pharmacy than usual, paid cash and didn't offer my SSN.
Look under Find a Physician in the menu on this page, the Verified and the Telemedicine sections have docs that know TSM:
http://www.cthreefoundation.org/home.htmlAs far as frequency goes, the general guidance is to drink when you crave (after taking the pill and waiting an hour). Sounds like you're restricted to weekends though, until you get past the side effects. Once you can drink on the weekdays without too much fallout, proceed at will. The perfect TSM drinking session is one and done, but not everyone can manage that. After the first, look for reasons to go dry for the rest of the night if you can feel ok about that. The dry side will start to look more attractive and the urge to drink will start to fade, so if you're ever on the fence about the next drink,
really consider hanging it up for the rest of the evening and letting your BAC drop back down towards normal.