The main thing is as someone mentioned above, she is not going to get help unless she thinks it is her idea. I am not totally convinced that she has mental illness. She sounds like she could be going through a mid life crisis, acting out and being a drama queen. If she has not made any more serious suicide attempts or does not talk about it consistently, she have been trying to get attention. It does sound like she does behave in attention seeking behavior.

Don't get me wrong, I take suicide threats seriously. I've been there myself. People do seem to get lots of attention if they take overdoses even if they are not fatal. Problem is if they do it to get attention and accidentally do take the magic combination of drugs for them. The alcohol use is a major problem, probably at the root of a lot of her issues. Again, that won't improve if she does not want to change.

Sounds like she needs someone to confide in and take interest in helping her to see the err of her self destructive ways. Is there anyone like that in her life? I know that you are concerned for her, I understand. Maybe a medical diagnosis is not what she needs. I know that getting diagnosed myself did not help me, is not helping me now whatsoever.

These are all just my thoughts, not any professional opinion. I wish you the best with this situation.