Agh, so frustrating. The problem is that doctors can take some of your discharge through a swab and put it under a microscope. They can see exactly what it consists of. If it has bacteria, they see it, yeast, or whatever else. And our swab comes back with group B strep. Things is, 25 percent of all healthy women have group b strep in the vagina. It's only a problem when they become pregnant as it is dangerous for the baby during delivery.
Anyway, here is Group B strep information. https://www.mayoclinic.org/diseases-conditions/group-b-strep/symptoms-causes/syc-20351729. You are right, they don't normally treat it in healthy adults. But have you had a physical lately? Any underlying conditions are good to rule out such as diabetes.
Vaginitis, read this and see what you think. https://www.webmd.com/women/guide/sexual-health-vaginal-infections#1