She probebly would have eaten them by now if they weren't fertalized.
Usually females hold for 2-4 weeks before spitting the babies. For younger and smaller fish they tend to hold for a shorter amount of time - 2-3 weeks.
Yeah... sometimes females can hold out but usually they learn to eat a little while still holding (how they do it i have no clue!). Some get so hungry they give up (usually thats the younger fish).
i had fuelleborni and the female held for about 2 weeks, then i had a load of babies, the female didn't look all that skinny. Also i had no other fish in the tank at that time, only the male and female fuelleborni