I'm 31 and a year ago my drinking was probably similar to yours...I was forced to limit due to an interlock device in my car and being female I discovered I could only process 7 beers a night before not being able to start the car and get to work...from there I had the same realization that it was not fun just numbing myself night after night. In june I cut down to weekends only. I have been completely sober since 11/15/09 and already I feel much better. Like a weight has been lifted and my mind is clearing up little by little. I have a lot of emotions now, good and bad, but I like that I am feeling again not living life in a blurry haze of nothing.
I would talk to your doctor about your health-it would seem to me like healthwise sobriety will always benefit you, but you may need help from your doc to safely quit. Good luck to you and hope you stick around-this site has helped me more than I can begin to tell you.