I would also fit your GF's style of drinking. Abstained during two pregnancies. Occasionally had too much and got ill or badly hungover, but maybe a few times a year. After my second child, my consumption escalated. And I gained a lot of weight as well. We cannot keep up that degree of caloric intake forever either.
At its worst, I was drinking as much as a bottle of wine most nights, maybe less on weeknights, skipping nights here and there, and more than bottle on the weekends. Once in awhile I got into fruity martinis or Margaritas. The trends.
I do not think I realized I was alcoholic until I actually truly tried to stop. I knew I drank heavily and more than was healthy. And my reason to quit was related to health consequences: Diabetes, overweight, and liver issues at 45 years old(49 now). I easily quit for 4-5 months at that time and all my blood work war normal, and I was told, *by my liver doctor* a glass of wine out to dinner, on the weekend, etc... would be ok. Well, there I was, doing fine for a bit, but then my drinking escalated and I have had trouble with moderating it to that degree.
It was only when I really had to stop, and could not, that I realized I do have a serious problem.
So, your GF may not see it, just like I did not. Even if not alcoholic, that quantity of drinking is not at all healthy. Maybe her tolerance it high, but her BAC is still going to be up, and she is doing damage ot her body, and should not drive, no matter how fine she may seem.
I am in the camp that think the label is not as important as considering the consequences of heavy drinking, in general: poor health, weigh gain, relationship troubles, etc... You are already having some issue with it affecting your relationship, since you have argued about it and it is bothering you.
I hope she can listen and hear your concern. I would love the support of my partner in this.