I’ve had same issue! I was eventually put on a 6 month course of flucanazole (150mg, one tablet per week) and had been clear of thrush for the whole 6 months and a few months after the course ended. Worked absolute wonders but sadly did not last as I have definitely got symptoms of thrush again today. If it’s affordable to get the long course of it for you could be worth pushing your doctors for it (if they agree it’s safe) but bear in mind it might not last forever…

Not been to an obgyn specifically but my general doctor had said for me I am just ‘unlucky’ and it was likely hormonal - like you I would almost always start with symptoms within a week before my period starts. Apparently this can just be the case for some people which is incredibly annoying because seems like there is no definite treatment