First, many, many thanks to you for taking in Mama Dog and her large litter. In most jurisdictions, the odds are they all would have been put down. You have given them a
solid chance at life.
Regarding "... trying to sort out her runny tummy, chicken and rice and a little pumpkin, just a little amount of puppy food, which I didn't plan on ..." - She NEEDS to be on high quality puppy food while she's nursing the litter, and typically twice as much food as a non-lactating female. Puppy food has significantly higher nutrient levels than adult food and she needs to take in nutrients for herself
and the puppies. Her GI issues are probably due to stress and food change, but also keep a close eye on the puppies. If they start having GI problems too, get everyone to a vet ASAP to make sure they don't have parvo.
Hoping all do well and thrive, even though we will all be jealous when you get to smell PUPPY BREATH!