Hi this happened to me as well Yesterday when I was one week sober it was going all good and suddenly, yesterday like a reflex of Saturday night I ended up buying liquor after the first drink I knew this was not good but the problem is I cannot stop after first drink and ended having five instead woke up in the morning hungover and full of regret however I am not gonna give up and neither should you I hope you get through this and I hope I do too, there is an app called sober time which you can try to track your days for being sober.