My image of an alcoholic when I was growing up was also the "skid row bum." This kept me from understanding for a long time that my father was an alcoholic. Because he had a job. And friends. And my mother pretending everything was A-OK! It also kept me in a world of shame and denial. How could I tell anyone what was going on at home? Would they think my dad was a skid row bum? All very confusing for kid.
Unfortunately, alcoholism is a progressive disease, and all the people who you think don't know anything eventually know everything and they are either in denial or afraid to speak up or both!
Your mom's level of drinking and her behavior while drinking would be red flags for me - but I have lived with alcoholism all my life (have 3 alkie bros) and through AlAnon I have developed my own little kit of tools to help me keep my mental heath and not enable the alcoholics around me.
Can you try AlAnon? Or do you have a one-on-one counselor you could discuss this with?
One thing I found out was that the years of denial and shame and pent-up rage in my childhood had created some bad habits of mind in me -- AlAnon and therapy helped me straighten that out - regardless of whether people are actively alcoholic around me or not!
Welcome, and keep reading around the forum - this is a great site for info and support. You can only help you - your mother's choices are her own.
peace,
b