Welcome, Lakia! For me personally, it was when attempts to limit or moderate my drinking repeatedly failed, when I would abstain for long periods of time, then pick up right where I left off, when friends and family started to let me know I was hurting them, when I became worse at keeping promises, when I started to become ashamed of my drinking and try to hide it, when I started to see consequences of my actions. I could go on and on.
And for what it's worth, I'm financially successful, have a good job and family, a master's degree, etc. Not unlike how you describe yourself.
Functioning alcoholic, non-functioning alcoholic...the road leads to the same place for all of us. I believe AA describes these places as "jails, institutions, and death." Some of us are just a little further along on the progression than others, ya know?
Stick around and keep reading and posting...it helps!