is an autoimmune disorder, one which is caused due to antibodies
(killer cells) produced by the body against its own tissues. Why and how the body does this nobody knows? However, (believe it or not) physical complaints are usually preceded by emotional imbalance, as is evident in your case as depression
Hypothyroidism is characterized by deficient thyroid hormone production which may affect ovulation and thereby menstruation
and fertility. Conservative medications are substituted synthetic hormonal pills and require day to day use for controlling hypothyroidism. However, use of these medicines have no effect on menstrual disorders, PCOD or weight gain. One would need additional medicinal therapy for each one of these.
From experience, homoeopathic remedies like Thyroidinum, Calc Iod, Bromium, Pulsatilla, Iodum would address all issues presenting with low thyroid hormone levels including regularising menstrual cycles, check weight gain, take care of the sluggish metabolism