What Causes A Delayed Menstrual Period?

I have been told I have a fatty liver in the past and I continued to drink. I had an ultrasound about a year ago that was negative for cirrhosis. I am 29 years old have finally put the alcohol down after about 6 years of heavy drinking. I have had a few signs but the newest one starting this month is that I am about a week late on my period and now I am very worried. Do you think I may have it now...especially since I am so young?