Hey Concerned--not much to add but will echo what many have said already. It's difficult to judge based on quantity alone. Beyond general health concerns, her attachment could be "only" psychological at this point, masked by "just enjoying it."
But if your GF drinks daily, there's a good chance that her habits will progress to drinking heavily daily, and if she does that long enough (for me it was years), she'll eventually reach the point of true physical dependency. And, as you already know from your work on your major, if she crosses that line it's a whole new ball game.
I empathize with the tricky spot you're in, though. Many of us responded poorly to loved ones who were concerned, not wanting to be controlled or told what was good for us. Your plan sounds like a good one. I would prepare well for the second part of that plan: how you'll respond if she answers your questions with "No, I'm not worried, don't have a problem, and you shouldn't worry either." Gently informing her of how this situation affects you is certainly a good place to start.
Good luck, BF. Let us know how it goes.