update on the granny situation or should I say down date

My darling daughter went for her 1st scan today, it seems the doctor made a basic error. he estimated the pregnancy from my daughters last period. Despite the fact that she has poly cystic ovaries and only has them once every 3 or 4 months. She's only 4 to 6 weeks pregnant. So I'll now be a granny in approximatly 8 months. At least all is well, and DD is still over the moon, and granny will just have to be patient for a bit longer. Why do I keep calling myself Granny. I'm definatly not going to be granny . I'm definatly nanny.