Is it possible that your mom has been an alcoholic all along? You say there was emotional and verbal abuse in your childhood, so I just wonder. Perhaps she was always an alcoholic and it was easier to hide the actual drinking from you while you were still young. Just because the alcoholism was hidden from you, or was not as progressed as it became in your 20's, it doesn't mean you weren't affected by it and it doesn't mean you aren't an ACOA.
Both of my parents are alcoholic but to be honest with you I have no memories of EVER seeing either of them drink or be drunk. That doesn't mean I'm not an ACOA, it just means they hid it from me!
The main reason why I never saw my dad drink is because he pretty much completely dropped out of my life when my parents split up when I was about a year old. I've only met him about 4 or 5 times in my life. I've had to deal with abandonment issues my whole life, this is how his alcoholism affects me.
I also never saw my mother drink, she would do it after I went to bed and then she also got sober when I was around 7 years old. But even after she got sober life was still chaotic for me, and she treated me like a mini-adult who was supposed to fix all her problems. There were lots of ways that her alcoholism affected me, despite the fact that I never saw her stumbling around with a drink in her hand.
Alcoholism is a progressive disease, so I suspect that your mother's alcoholism didn't just suddenly spring forth once you became an adult, it was probably lurking all along and affecting your formative years in some ways that have yet to be seen. Are you seeing a therapist? I found that going to therapy was really essential to me when I started working through this stuff. Helped me really stay pointed in the right direction and my therapist really helped me to stop minimizing and excusing my parent's behavior.