Your itching has lasted a year despite trying powders and creams, so it's time for a proper look rather than another product. PCOS can make you more prone to fungal irritation, and it tends to linger if the real trigger isn't treated.
Next Steps
Please see a gynaecologist who can examine you and take a swab if needed before prescribing anything.
Health Tips
Avoid trying more creams on your own, since the wrong one can worsen irritation or hide what's actually going on.