If you are there 5 times a WEEK to babysit while she takes her puppies to the vet...then she is obviously a mill. No reputable breeder has that many litters that they need to go to the vet 5 times a week (or month!) to take puppies for vaccinations.
If she had 13 litters at least in March and April...hello, that is a puppy mill my friend. Most breeders don't have that many in a year. She may be a nice person, she may love animals, but all that aside, it's a mill.