E.K.
Hi L.,
Ok, first: stay calm! You and your baby will be fine. You will get antibiotics during labor (they want you to arrive at first sign of labor and get started on those meds.).
GBS is pretty common and it colonizes in the gut. It's one of those things that you can test positive for one week and negative the next(I'm not explaining it properly-I have mommy brain).
Since you tested positive and will be getting antibiotics, the next (small)worry is yeast infections and thrush. Just talk to your doctor. Consider doing some more GBS research on natural childbirth websites.....they are sensible and not scary. You can learn about how diet and homeopathy can make your gut less hospitable to GBS, if you plan on having more babies after this DS.
DON'T WORRY! You and baby will be fine.