I wouldn't be worried about her quite yet. Maybe give her 10 or 15 more days. Keeping the water warmer and feeding them high protein food, either frozen, freeze dried or live can encourage spawning.
Just warning you, Mollies and pretty much any other fish like to eat the fry so if you want to give them a better chance of survival, either take the momma out into a seperate tank while she is giving birth or scoop out the fry and put them in a seperate tank to protect them. Good Luck!