Not all alcoholics drink every day. Many are binge drinkers who can go days, weeks, even months without drinking. When they do drink though, they almost always overdo it and end up drunk. Alcoholism is not determined by how often a person drinks or even how much they drink, but by how they are affected when they do drink.
I remember you from some other threads. From what I've read so far, your daughter is playing with fire and making some extremely dangerous decisions when she drinks. I believe you said she came home drunk with a friend and was only half dressed and said they had been out with some guys. She is engaging in very dangerous activity.