From the little that I've read of 'the book'..... The issue isn't really quantity of alcohol, but rather understanding the disease itself has a key component known as the phenomenom of 'craving'. So if i were in your shoes, I'd ask myself 'Why did I have 1, 2 or 3 beers'. I know for a fact if I'm honest with myself about that answer its because i damn well craved that taste in my mouth and was yearning to feel that cold frothy drink go down my throat.
Why was I craving it? Not because I have 4 12 packs of seltzer in my fridge which provides a similar physical sensation, but because my MIND tells my body to crave that sensation so it can get the 'high' (or buzz) its psychologically craving - To that.... I can't control (yet).
To your question - I believe the question you want to ask yourself is WHY did I have 3 beers?
I'm open to correction and feedback on my theory