Hi Mel, sorry I think you know a heck of a lot more than me about it all, LOL! So I don't think I'm going to be any help to you.
Firstly, welcome to BB and congratulations on your pregnancy!
I know I was told to get Nilstat pessaries if the canesten didn't work when I was first pg. It doesn't have an applicator. I assume they are safe, but I'd only be going on what my GP said too...
As a preventative measure, I haven't heard of any of those things, LOL, so can't comment unfortunately. You may have already tried this, but my sister lives in the tropics and swears by Yakult as both a preventative measure and treatment. I imagine it'd get fairly expensive, as she says the 'home brands' don't work.
I hope you find some relief soon!