Chaste-Berry: (agnus-castus) This herb, when consumed, behaves as a hormone (although it is not) to initiate a menstrual cycle in those women that do not have normal, monthly cycles. 

It has been used , in European countries, for quite some time just for this very malady. Without getting too technical this berry extract works in conjuction with the hypothalamus and pituitary glands.  It encourages an increase in "lutenizing hormone ( LH)" and decreases the release of the follicle stimulating hormone (FSH). Producing a normal cycle.

Amenorrhea (absence of menstruation) is caused by the body's reproductive organs, not ovulating. Thus making it an this herbs extract a perfect remedy for amenorrhea or infertility.

Adverse Side Effects:  In one study, chaste - berry was given for 9 years with very few side effects.
It's advisable to not take herb if you are pregnant.