
Temperature taking can be a useful guide re at what stage a bitch has reached, but in fact I never held that as important as counting from the first mating, bearing in mind conception may not have taken place immediately.
I never let mine go over by more than a couple of days however.
Another point - if she's only carrying a few, they may 'sit' which is ok except they are growing bigger by the day and that may end up in her needing a C.Section.