How long after you finished chemotherapy for breast cancer till your periods are regular?

Some times never: Younger age periods will come from 2 to 6 months most of the time in some never come back especially little older group will be menopausal at 40 , also ovum could be defective, congenital abnormalities is possible , must discuss with oncologist , for possible freezing of ovum before therapy and ivf in future.

Varies: It can take up to a year but I have seen it take longer. Hope this helps.