FreeOwl,
just a couple of thoughts:
it is not necessary or always possible to figure out or have an idea of what her issues are, and i don't see that entering into the amends-process, since that is about amending your part.
since you do not know your part but can see that she is resentful/ distressed/upset/ angry/whatever, you cannot make a direct amend when you do not know the harm you caused or if, indeed, it was you who caused anything, but you could possibly,if you wanted, follow miamifellows suggestion to ask directly.
another thought is that possibly your part in any of it was simply that you did not make the effort o have a closer relationship?
personally, i do not see that whether a person has a drinking issue or any kind of issue has anything to do with whether i make amends or not. Irrelevant. if i have harmed them, i owe amend.
just from reading and trying to imagine being in your shoes, i'd mention to her that she seems upset with me a lot and i'd like us to be able to chat about it and could she tell me what i have done and i'd like to hear about it and make amends if i have caused her harm.
I'd take that route if i were willing to hear.