There is not necessarily a problem at all.
The date "you stick her" isn't necessarily the day her eggs are ready
Suppose, on the
last day you stuck her, that her eggs weren't ready for another
4 days. Since the semen can live for 5 days, she just got fertilized later than the date she was stuck, and that means you took her to the vet on Day 63
from when she was ready ... and she
still might not be ready to give birth for another 2-3 days, which is longer than usual, but still within normal parameters.
Not saying that what you did was "wrong," per se, but she might not have had a problem at all. If her pups were fine, and she was healthy and eating, then there was no 'problem' actually present, just a bitch who hadn't yet gone into labor ... and a worried owner
Jack