I think there are a few members here who have had rather large litters. Someone had 7 not long ago if I'm not mistaken.
If she is due on the 19th, you should be able to get and x-ray done in a week or so and that should give you a good indication as to if you should expect a large litter. They don't always give an exact number, but you'll have a good idea of what to expect.
