okay, well, honestly, I wouldn't worry too much about GBS. you have no way of knowing if you have an active infection, unless you were tested positive, like, yesterday. and that's no surety that your baby would be infected, and even then, not guaranteed it would be a problem.
you can take quite a large dose of vitC. how much did you take? do you know what your tolerance dose is? you should be able to take at least 3,000mg in a day before reaching tolerance (diarrhoea). and in any case, getting a little case of the runs might not be such a bad thing - it's known to trigger labour
if you're still having little leaks when moving, it sounds like you do indeed have a leak.
still, I wouldn't worry toooo much about getting labour jumpstarted at this point. I've seen many women with a small leak (even one with a huge gush) then go on to start labour several days or even a week later without problems. if it's ready to start, it will.
nipple stim is easy. just twiddle and rub your nipples firmly for at least 20 mins. if you have a partner or someone else close, you can let them suck. your electric breast pump would also work very nicely.
anyways, i'm online now, so let me know how it's going