Laura Mckowen has written an article that everyone who has ever asked this question needs to read: http://www.lauramckowen.com/blog/2017/4/15/am-i-an-alcoholic
This is one of those pieces where whilst reading it I shout halleluiah, amen and testifyyyyyyy at the the top of my lungs. Yip I am the crazy lady alone in the house shouting at her computer.
Do yourself a favour and read it. I fucking love it.