Thanks for answering my questions. I really appreciate it Charlie.
Unfortunately, in the absence of any other symptoms, I can't help but wonder if she's having a false pregnancy.
Pseudocyesis (false pregnancy) often occurs when a dog has been bred but doesn't get pregnant. You can find more information about this here:
Unfortunately, there isn't anything you can do to get a dog to stop lactating after a false pregnancy. They have this lactation issue strictly due to hormonal imbalance and the body thinking that there are puppies to nurse. This issue will usually clear up on it's own after a few weeks.
If it doesn't, or if you notice any swelling to the mammary chains, lethargy, anorexia, vomiting or diarrhea or heat to the touch on the mammary chains, these are all signs of an infection that needs to be looked at by a vet as soon as possible.
If you want to avoid these issues in the future (some studies indicate that once a dog has a false pregnancy, they are more likely to have them again), it's best to have her spayed as soon as possible. That will also eliminate the possibility of unwanted puppies, mammary cancers and a uterine infection known as pyometra.
Of course, we're not exactly sure if this is what is going on with her...so since she's not acting like she's in distress or having any signs of impending labor, then I would suggest you call your vet in the morning and have them take an x-ray. They'll be able to count the spines if there are any babies, which will help them know if she's pregnant.
I hope this helps.