Hi, I understand your concern regarding the missed periods. After stopping the oral contraceptive pill the return to a normal pattern of menstruation may require some time. Some women begin to have regular periods from the first month. But in some cases it may take upto 3 months for the return of periods. Since the pregnancy test is negative, if you have not used any other contraceptive measure, repeat the test after 10-15days preferably by using the first morning sample of urine. In some women, ovulation may be erratic and may not always occur on the predicted day of the cycle which is usually day 14 from the first day of menses when women stop using OC pills. Hence the timing of conceiving and becoming pregnant is difficult to predict. The repeat test helps in detecting a pregnancy that may have occurred at a later date. Meanwhile I would recommend that you use some other contraceptive like condoms if pregnancy is not desirable. If the pregnancy test it is still negative and pregnancy is not desirable then continue to use some other method like condoms and wait for upto 3 months if everything else is fine. If the periods still do not return she may need further evaluation and have an ultrasound examination as well as a hormonal workup done to evaluate the cause. hope this helps you and please do not worry as the matter does not appear to be a complex one at present.