The behavior you’re describing does not sound like addiction. People with an addiction to a drug feel compelled to use the drug and become distressed if the drug is unavailable.

This is also not binge drinking by any commonly-used definition. Two pints of beer a day is generally considered moderate drinking, and you’re not doing it every day, only when beer is on sale. Research does seem to be converging on drinking alcohol at all being bad for your health, however the effect size for occasional moderate drinking is small enough that it has been difficult to measure.

What you are describing is impulsive behavior. When you see beer on sale, you can’t resist taking advantage of the offer. When you have beer, you drink it faster than you meant to. If you think about other areas of your life, can you find more examples where you struggle with impulse control?