Hi,
I am a SAHM to a smart and handsome 26 month old and a beautiful 6 month old daughter. I am also nursing and have researched and asked lactation professionals about both caffeine and alcohol (wine, on occasion). Much of what I have read says that it runs through your breastmilk just like it would run through your system. I believe I was told about 3-4 hours for caffeine to run out of my system and about 1-2 hours after finishing a beverage for it to run out of my system. As a new Mommy I know how it is to need a caffeine boost for some of those sleepless nights. My baby girl will not sleep well if I have caffeine too late in the day. Also I have noticed now that some things that would bother her when she was smaller, do not affect her as much now. Her stomach must be growing tougher.
Anyways, I'm sure you know that this stage does not last long and the baby will be grown before we know it. So just enjoy breastfeeding while you can and congrats on your precious bundle!