There is a good chance that your girl isn't pregnant with them both being so young.
If she is pregnant then she should be showing around her 6th to 7th week.
At 55 days if you feel she is pregnant, take her into the vet for an xray. This will tell if she is pregnant, how many puppies she may have and whether they are a good size for her to pass naturally.
In the mean time you should be reading up on the whelping process so you are prepared. You should also see if you can find someone around you who is experienced to help you and can be there with you during the delivery to guide you. You also need to make sure you have all the whelping supplies on hand before the due date.
Here is a great site with lots of information on the whole process.
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies.
Good luck!!
