Do you know when she actually ovulated? I would only go to the vet if you hit day 65 from ovulation and still have no puppies. If you didn't progesterone test, that won't be useful as you won't know exactly when ovulation was.
With her temperature, most bitches in their final weeks have temps around 100F, but fluctuate from 99.5F to 100.5F. Temps will often be higher in the morning and drop as the day goes on, so try to take them at the same time of day. You are looking for a LARGE temperature drop that persists at least 8hrs - this will then be 24-36hrs prior to whelping. So - 2 consecutive readings with temps at 99F or lower. (Some will go as low as 97F.) Make sure you have a decent thermometer.
You want to see the first visible contractions within 36hrs of the start of her temperature drop - if not, go to the vet.