ANSWER - Very interesting question - the idea of subconscious casting comes up a lot in discussions. I’d say to some extent most of the witches I know would acknowledge that they have achieved results without deliberately seeking to bring them about. Certainly I’d identify with that – things pretty much always go my way whether I intentionally cast magic to bring that about or not.
In the specific case that you discuss in your question the deciding factor for me would be whether the effects are temporary or consistent. I don’t think a witch (certainly not a witch in control of herself) could bring about a permanent mind altering spell without consciously focusing intent but I do think she could ramp up the wattage of her personality to the point where she becomes dazzling and very attractive to you on all levels.
I think it is very likely that in a state of heightened emotion brought on by the alcohol this witch is certainly projecting her charms to you so strongly that you cannot help but have feelings for her. This doesn’t mean she is doing it intentionally or that there is any malice on her part, she may well not know she is doing it.
We are also biologically designed to be very addicted to the feelings that love inspires in us so if each time you spend time with this witch drunk she is arousing these heady feelings in you it is unsurprising that you can’t get her out of your head. I don’t think that means she is intentionally implanting herself there, more that you are keen for your next fix of the love rush.
If your feelings are lingering beyond the moment then my money would be on the fact that they are genuine and more about what you naturally feel for her than anything she has done to you. Love magic is popularly portrayed as being quite easy to cast but in fact anything that alters free will is pretty complex magic indeed and hard to pull off. You do seem to be discounting the possibility by the way that she is not doing this subconsciously? If she’s focusing her intent and effort into this then it is definitely plausible that she can elicit feelings of love from you.
In a nutshell – yes it is possible.