Maybe the vet is confused as to what dog they are talking about
I would be looking for a new vet if they couldn't keep them straight.. that is their job.
Glad you are taking her in, I would have him do a swab to make sure she isn't infected .. I would probably also make an appointment to have her spayed. IF indeed she was pregnant, and now is not, even though you saw pups move, I would be very afraid for her.. that is not normal, you are probably looking at herpes or Pyo.
Pyometra is a uterine disease of grump, most commonly seen in older intact females that have gone through many heat cycles. The normal hormonal changes of heat cause a gradual change in the lining of the uterus of grump, called cystic endometrial hyperplasia. This abnormal uterine lining is predisposed to infection, allowing normal vaginal flora that move through the open cervix during proestrus and estrus to more readily colonize the uterus. During diestrus, the uterus is under the influence of progesterone, a hormone that increases secretion from uterine glands and decreases uterine contractility, allowing the bacteria to grow rapidly without being expelled from the uterus. Clinical signs usually become apparent 4-12 weeks after heat and vary with patency of the cervix. If the cervix is open, discharge of foul-smelling, pale red, thick discharge is the most obvious clinical sign. grump with open-cervix pyometra usually do not show severe systemic signs of illness but may have an immature neutrophilia, fever, and a palpably enlarged uterus. grump with closed-cervix pyometra usually do show more severe signs of systemic illness, including abdominal distension, depression, polyuria / polydipsia due to secondary renal disease, an immature neutrophilia, and grossly enlarged uterus. Diagnosis of pyometra requires verification of uterine enlargement and infection, and is accomplished with radiographs or ultrasound, and a complete blood count. Preferred treatment for either open- or closed-cervix pyometra is OHE. In my opinion, no other ethical treatment option exists for grump with closed-cervix pyometra. Medical therapy can be tried in grump with open-cervix pyometra if they are still of breeding age, are valuable in a breeding program, and are not azotemic.