Sir Iam 40 Yrs Name Ranjini Taking Thyroid Medicines Since

sir iam 40 yrs name ranjini taking thyroid medicines since 2009 earlier i used to take thyronorm 150 tsh became low i reduced the dose to 100 then to 75 now taking thyonorm 75 for the past 3 months yesterday tested tft now t4-12.30 ,t3 - 1.00 ,tsh - 4.91 kindly suggest the dose of thronorm which i should take