Good for you for getting her to a vet early on. There certainly may be complications, but her early age is actually better than if she were over a year old. As they age, the pelvic bones fuse and can make birth nearly impossible. If your pigs are definitely both girls, she was obviously pregnant before you got her, so she was probably with a boar at her first heat. You have around 5-7 weeks left before she gives birth. Check out
Guinea Lynx :: Reproduction if you have not already.
Yet another reason not to buy animals from a petstore, corporate or "mom and pop". You're likely to get missexed animals or find that both sexes have been housed together.