Sadly this exact same thing happened to my girl in July, she ended up passing 4 mummified dead pups over 2 days, then another 2 WEEKS LATER
She stayed on anti-biotics for 4 weeks and so far so good, but she didn't have any live pups :-(
My vet also thinks she didn't deliver them all and that some are still inside where they will stay and calcify, which could affect her fertility in future. She was both scanned and x-rayed recently and as far as we could see everything had gone.
It was very sad and upsetting, but at least my Rosie is still with us and back to her 'normal' self, her tummy stayed big for a couple of weeks before it started shrinking back, my vet said her womb felt large and thick and would do until everything had settled down.
It sounds as though your girls pups died a while ago, 2.5cm at 7 weeks is too small!