K.R.
I was dx'd with severe bv around 7 mos; I prayed and cut almost all sugar from my diet, and it cleared up; that pregnancy went (very very) late.
I didn't take any meds while pregnant, including antibiotics. If a 'problem' came up, I considered it as an imbalance, and tried to find the lifestyle changes that would bring things into balance ... so I was coming at it a little differently than you I guess. But cutting sugar is at least an extremely logical way to stop bacterial overgrowth. (Also directly related to yeast infections.)
God bless. It sounds so scary, "bacterial vaginosis," and the threat of preterm birth; I think it made it harder to bring myself into health. It is a real risk, statistically supportable ... but make sure you have people, especially caretakers, around you who are telling you something besides "live in fear!"
Live in hope :).
--K. :).