Hello,
Welcome to healthcare magic.
The dark patches on your face could be
melasma, lichen plan us pigmentosus or Reihl' s
melanosis.
Since you have met 6 dermatologists, I presume an appropriate diagnosis has been made as each condition has a different prognosis.
However, some common steps you can follow are -
1. Always use a broad spectrum sunscreen with SPF 30 or above every 3 hours.
2. Cover your face with a scarf in addition to using a sunscreen.
3. Eat plenty of colored fruits and vegetables.
4. Take oral antioxidants.
5. You could try lightening agents containing
kojic acid,
liquorice, arbutin and niacinamide at bedtime.
6. You could try
chemical peels like glycolic peels and retinol peels.
Hope these help you.
Take care.