Ask your Doctor for an ultrasound scan, I was the same as you for only 5 years, felt fine, drank around 6 cans a day, sometimes 8, didn't put on much weight, I had a ultrasound scan done and they found I had fat starting to accumulate on the liver, this is something you don't feel but will lead to liver disease if not dealt with.
Quote from British Liver Trust,
"It is a mistake to think that you have to be a heavy drinker to run into problems. Although it can take as long as 10 to 20 years, drinking just a bit more than you should over time can seriously harm your liver. Not feeling any side effects from drinking does not mean that you are not risking chronic ill-health or lasting liver damage from alcohol-related liver disease. Vast numbers of us now fall into this category.
The liver is your largest internal organ. Among hundreds of jobs, it has to deal with the alcohol you drink. If you’re drinking too much, your liver has to literally soak up the punishment. With so few nerve endings to signal pain you won’t know that your liver is complaining. If you’re drinking a lot on a regular basis, chances are that you will not feel anything happening until your liver has had enough. The harm to your liver at this stage will be severe – and could even be fatal."