Welcome James! I'm glad you've decided to take a cold, hard look at what alcohol is doing to you. Many of us have similar backgrounds to yours. Early in our drinking careers, we could handle it - only to find ourselves completely dependent on it later in life.
I'm sure you've heard the phrase, 'alcoholism is a progressive disease'. Over time, our tolerance grows. When I was in my 20's I got high on a few beers. In the end, a 30-pack a day wasn't enough to achieve the desired effect. Unlike you, I just kept on going with it - insisting willpower alone would work. It didn't. I almost lost my life proving that I can't touch a drop.
Please keep reading and posting. We're glad you've decided to reach out for a better life.