3.4 lbs...yikes!? That is waaaay too small to have even been bred.
No offense, but these are all things that you should have been prepared for
before breeding, not something to start worrying about a week before she is due.
<sigh> But what's done is done...that being said...
You should start counting from the date of the first tie.
I would difinately not leave her alone and have a vet on standby and aware of the situation.
It's not unheard of for a female to go a bit early, but not more than a week early!
Have you had her x-rayed yet? If not I would have this done ASAP. It will give your vet a good indication if any of the pups appear to have developed to large to be delivered naturally...which is a very good chance given that she is so small. It's better to have some sort of heads up vs chancing it and having to rush a female in distress in for an emergency c-section.
I'm not sure why you began taking her temperature a mere week after she was bred....?
A sudden change in temp is not
always present or evident with the onset of labor, so don't depend too much on that.
The best advice I think you can be given at this point is to try to plan with your vet or a very experienced breeder to see if they can assist you during the whelp.
Good Luck.