Hello Lisa, welcome to the forum.
You've raised a number of big questions here, I'll give you my take on them - but remember, it's just my take.
People start drinking for all sorts of reasons - to fit in, to relieve stress, just to have a nice glass of wine with dinner - all sorts of reasons, some bad and some perfectly natural. And many people go on drinking for these reasons. They may drink heavily at times, but usually it's not continuous. But for those of us who become alcoholics, something changes. It is almost like a switch being turned on in the brain, and we drink just to drink, there is no longer a reason for it. It is a completely irrational response. The psychologist Gabor Mate calls it "a bare want." That was the best description I ever found for my drinking, and that is what makes it so hard to resist.
As for how you get to the point where you want to stop - that too is a hard question. I think you get there before you get there - so to speak. I wanted to stop for years before I actually did. What seems to have happened to me is I got to a point where I was just too tired to go on. Alcoholic drinking just takes a lot of effort - people think it doesn't, but it does. It's no longer something you enjoy or want to do, but you keep doing it, and, as you say, it starts interfering with the rest of your life - and that just takes a lot of effort. I also stopped many times before I finally stopped for good - some times for weeks, sometimes for months. Some people just get to this point and stop, others have to struggle with it to finally get there.
My only advice is just to keep plugging away at it. Eventually you will get there. There will come a point where you can just stop. It may take several tries like it did for me, but you will get there. There is nothing special about those of us who stop. It we could do it, so can you. You just have to keep trying.
I gather you don't want to go to AA. Most of us here started with AA before we found Life Ring. What I would suggest, if there is no Life Ring meeting around where you are, is just go to an AA meeting just to be around people who are going through the same things you are. Just ignore the parts of the AA message you don't like, but it is very helpful to meet face to face with people who understand just what you are going to. I was lucky in that I found a very undoctrinaire AA meeting where the steps and the religious elements of AA were emphasized much, and I am able to ignore things I don't agree with. And while I didn't agree with much that was said, I did find many of the more practical discussions helpful.
And keep coming back here. You might also try reading some of the Journals people have posted here. They describe the day to day struggles people went through - some going on over years.
So good luck, hope to hear from you again.