I'm worried about her, do you think she has a drinking problem?

I think my mother may have a drinking problem. She never really used to drink much, and she never went out much. Then she got a boyfriend who she was with for 4 years, and he drank every night, so she did too. They would just sit in the porch and have a couple of beers, while she went on her computer. I would come in the room, and there would be a grocery bag full of usually around 12 cans (approx). This may not sound like that much, but this was going on every night, and she would come upstairs at around 1:00 fairly drunk for bed. They broke up, but it wasn’t a big deal because they weren’t in love or anything, believe me. Then she was fine, she stopped drinking for a week or so. Then she started going out for “coffee” every night, without telling me. She would come back around 2 o’clock in the morning, not drunk but close. I thought she was seeing someone and I was right. Turns out they weren’t a couple, but they were starting to date. Then he sort of dissapeared, I think with another woman he had also been seeing. Anyways, for around the past 5 days she has been getting drunk every night, either with my aunt who lives up the street, or by herself. I am getting sick of it, and I think she may have a drinking problem. What do you think about it, and what should I do? Sorry for the long story.. It sounds like this has been a recent habit of hers, but it has been going on for most of my life, just on and off. Right now it is pretty bad. Help?