I am worried about my mother

I am worried about my mother

I am worried about my mother. We are extremely close and we lost my father a few years ago.I live with mum and my 2 grown up brothers. we get on well. My mum has smoked for a number of years and tends to drink alcohol (approx 3-4 + drinks) in the evenings. Mostly she will drink a spirit with a mixer if she is not working the next day. I think she does this to relax. I have tried to help by offering other ways of occupying her time but I feel awful that I am picking on her. She puts up with a lot from me and will take what I say in her stride, but I feel awful and would hate to upset her. I love her so so much and want her to be happy. She said she knows I'm right but doesn't seem to stop. I mean, what is safe? am I overreacting?
THANK YOU X X