When a dog goes into labor, she should be having her first puppy within 30-40 minutes. At least, that's what I've been told.
From my understanding, toy breeds tend to have dystocia issues more than larger breeds. The vet needs to be called, this is a problem. She could have a stuck puppy.
Tbh, I'd be worried about a lot of stillborns by this point.
That is my understanding as well.
Two hours tops.