Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I understand that you are concerned about your girl and her pregnancy. I can give you some information about labor and delivery to help you prepare.
Normal length of pregnancy can be anywhere from 63 to 76 days, though most dogs deliver at about the 65th day. First pregnancies tend to go a little longer then subsequent pregnancies and generally the more puppies in a litter the shorter the length of pregnancy. So if she only has one or two pups she may have a longer pregnancy.
The most accurate sign of impending labor is a drop in body temperature, usually at least a couple degrees, down to less than 99.5F. At this point I recommend you start taking her rectal temperature every 12 hours. That way you will have an idea of what her normal is. When her body temperature drops below 100F she should be within 24 hours of labor and delivery.
Other signs to look for are restlessness and nesting behavior. Make sure she has a place set up for delivery now that she is very comfortable with. During her first stage of labor she will have some cramping and be restless but she won't actively be pushing.
Most dogs will start milk production a day or two before delivery but some start a week in advance and others don't start until the day of delivery. There are many variations of normal.
When she progresses to the second stage of labor that is the active stage of labor. The first puppy should be born within 2 hours of you noticing her straining and it is usually faster then that.
There shouldn't be more that an hour between puppies and if you see any fetal membranes or a body part protruding the pup should be delivered within 30 minutes, if not that signifies trouble. The problem can be a puppy that is too large to pass through the pelvic canal, improper presentation of the puppy or uterine inertia (poor muscle tone and contractions). She may need help getting the pup out of the fetal membranes. You can also help by tying off the umbilical cords with clean thread about a 1 inch from the body wall.
There should be a placenta delivered with each puppy. Some dogs will want to eat the placentas but I recommend removing them so they do not lead to stomach upset
When she is done delivering all the pups expect her to expel some blood, fluids and the remaining tissues from the pup's placentas.
She may or may not want to eat and drink after the pups. Have fresh food and water ready for her as she needs fluids and calories with all the work she has done. Some dogs however are too nervous or busy with their pups and will wait to eat and drink until later.
Here is a link to an accurate article that will help if you have any further questions and also describes possible complications after delivery: http://retiredvet.hubpages.com/hub/Pregnancy-and-Labor-in-Dogs
Has she had radiographs or an ultrasound done recently so that you know how many puppies to expect? That may be a good idea so you know how many puppies to expect.
It is possible that she is not pregnant and that this may be a false pregnancy. This can occur after a normal heat cycle, even with a breeding.
This is because hormonal changes in a dog are very similar whether they are bred or not.
In a pregnant dog the female's hormones fall off and the pups respond with their own hormones which leads to delivery.
In a nonpregnant dog there just isn't any pup stimulation. But some dog's bodies get confused and they feel like they are pregnant.
They may pick a toy to mother, may even build a nest and produce milk.
We do know that if a bitch's mother had false pregnancies then she is likely to have them as well. And once they have one false pregnancy they are likely to have one with every heat cycle where a successful breeding doesn't take place.
It doesn't mean that she isn't fertile or that there are hormonal problems with her. She could be successfully bred on her next heat if you wanted to. If she hasn't had radiographs taken then I would strongly consider having them done.
If she is within 2 weeks of delivery she should be switched over gradually to a high quality canned puppy food diet which she should continue eating as long as she is nursing. This will supply the additional nutrients that she needs to try to maintain her body weight and feed puppies.
Best of luck with your girl, hopefully you will have healthy pups soon. Let me know if something I've written wasn't clear or you have more questions.