
With her parents beign such disparate sizes then you can only guess. Some of the litter could be as small as the smaller parent and some as large as the bigger, and anything in between.
In my own breed where I want them to be about 19 1/2 for bitches and 20 1/2 for dogs I would be happy with them being 18 inches at the shoulder at 6 months, but different breeds vary in their growth patterns so much.