The persistent yeast and bacteria infections strongly suggest you body is severely out of balance.
You could try the following:
1. Look at your lifestyle and general happiness. Are you stressed out, unhappy about something? This will lower you immunity and by itself, can give rise to vaginal infections.
2. How is your diet? To get rid of yeast, eliminating sugar, white flour products and all junk is essential. Eat low glycemic (foods that are low in fast releasing sugars and other carbs), increase leafy veggies, salads, some good whole grains like millet, buckwheat, quinoa. Eat live unsweetened yogurt, preferably homemade.
3. Medicinal foods/herbs for yeast, BV are :
To reduce infestation:
Lots of GARLIC, Pau d'Arco tea (buy the real thing), olive leaf extract capsules, neem. You can try inserting a whole clove of garlic (don't cut it, it will sting) into the vagina overnight for a few days. Goldenseal, tea tree oil and myrrh are highly effective, too (can use locally as douches, bolus or mixed in yogurt), but have to be used with caution in pregnancy.
To build resistance:
Echinacea, Vitamin C (reduce dosage towards end of pregnancy)
To repopulate the vagina and gut with good bacteria:
High potency probiotic 2-3 times daily, orally.
You can also try homeopathic remedies, like Sepia. But do read up about it first to match your symptoms.
I am surprised the yogurt made your symptoms worse. was it live, unsweetened yogurt? Sugar would feed the yeast. i use live yogurt and add a drop of tea tree and lavender oil each.
For herbs compatible with pregnancy, check:http://www.growinglife.com/herbalsafety.htm#pregnancy
It is disputed whether or not Strep B carriers really benefit from IV Antibiotics during labor. Babies may then end up having Antibiotic resistant strains of bacteria.