Hey there! I'm in your ddc and came over here from there. This is pretty close to what I just went through. The problem with doing the GBS now and waiting on the results is that they take 48 hrs for even a preliminary result, and most midwives (certainly all docs) would want you delivered before then - usually WAY before then.
We broke our water, with significantly more fluid loss than what you're describing, and went ahead and did the abx (IV) for 48 hrs while waiting on a GBS result. It came back negative, and we went another 6 days (8 days total) before I had any infection set in. And I had NO labor whatsoever until about 8 hours AFTER I started showing signs & symptoms of infection. We were super careful with hygeine - bathroom and bedroom scrubbed til they shined (by hubby, not me - I was confined to bed), lysol spray everywhere LOL, NOTHING touching me down there except water with a little betadine from the peri bottle, and wiping after potty as needed. NO baths, NO exams, NO sex, etc. Fresh pad every two hours whether I needed it or not (I usually did).
You CAN certainly go more than 24 or 48 hours without getting an infection, without antibiotics. There's no guarantee, though, and that's why medical practitioners get antsy, and want you to just deliver - because they know the baby will do fine once out (as long as you're term or close to it). It's definately a personal call - I've heard stories that infection can be set in and baby in trouble long before mama shows any signs or symptoms, and I've heard just as many about mama waiting for labor to get rolling on it's own and never did have any infection. In my experience, I had plenty of time, and it made all the difference in the world (our LO was born at 34w6d and got apgars of 9/9).
I would say trust your instincts - we were all about going home from the hospital and waiting it out, until about 3 days before she was born. Then all of a sudden, we got really anxious, felt like we were pushing our luck, second guessing ourselves, etc. Turns out, that's most likely when the infection started setting it, and it just took 3 days for me to show any sign of it and for it to start impacting the baby. If you feel really confident about waiting, then wait! If you feel really nervous, then kick those natural induction techniques into high gear. If you've been having some contractions, there's a good chance that you're close to being ready anyways, and they'll work. Look up the Gentle Birth archives for lots of natural induction ideas, and share them with your midwife. If you're COMMITTED to delivering within a certain time frame, she may want to do an internal exam and put some EPO on your cervix, etc. BUT, only consider that if you're prepared to hit the hospital and pit drip in a certain number of hours, because internals are exactly how women DO get infections.
Anyway, I hope it all goes the way you want and can't wait to hear about your new little baby!
Tracey R. Happy Helpmeet to Jeff, and Mama to Corey (ds, 22yo), Justin (ds, 20yo), Bekah (dd, 3yo), and Miah (Jeremiah, ds, 17mo), and baby Rachel, vasa previa survivor, 4 wks old.