Hi widdly,

I think its very understandable that you are concerned about this, however, as Mel said, its probably best to wait and see how your pg goes, and to talk to your GP/Dr/midwife about your concerns. As it may well be that your perlvis is a different size/shape than your mothers. Also, I would caution against relying 100% on the results of those scans where they estimate size/weight before birth, as I have heard its not too uncommon for those measurements to turn out to be innacurate.
I also agree with what Mel said about doing your research into the kind of birth that you want. As an informed decision is an empowered one.

All the best