Hyperthyroid. Start taking ashwagandha?

It’s been 6 months I’m under medication(Neomercazole) for Hyperthyroid 1st 2months 20 mg, next 2 months 10 mg , current I’m In my 6th month of medication with 5mg for Hyperthyroid. As symptoms going on and off some times , but there isn’t no change in my weight. I’m trying to put on some weight, it is not happening with Hyperthyroid. Can I start taking Ashwagandha? Will there be any side effects if I stop my current medicine and start taking Ashwagandha ? Below are my blood results from last 4 months: Initial Blood Test results : FREE T3,T4 : 2.41ng/dL TSH : 0.01 uIU/ mL After 2 Months of medication 20mg : T3 : 0.99 ng/ml T4 : 8.77 ug/dl TSH : 0.66 uIU/ mL After 4 months of Medication 10mg : FT3 : 2.64 FT4 : 0.59 TSH : 21.21 I'm due for my 6 month blood tests.