How Can Periods Be Regularized?

iam 21 yrs old female.. 167cm and 78 kgs.. iam taking treatment for thyroid for more than 3 yrs.. i have scanty periods... weight gain also.. my stomach is too hard.. i often get stomach pains and frequently indigestion... iam taking thyrox 25mg and shelgal 250 mg... but there is no improvement in my health... is there something to be done to regularize my periods?? also to reduce my weight??