Hi and thanks for the query, absence of periods in females of reproductive age or period delays should make one think of a pregnancy. However, the use of pills might actually cause period delays. Pills are hormones and certainly interfere when the normal metabolism and balance of the hormonal control system when used. I might suggest you just be patient again for a week or two and do a control pregnancy test. If not, its better to do serum beta HCG test which is more sensitive and if case of continues doubt or conflicting results could demand an abdominal ultrasound to clear the doubts. In case in a week or two you fail to see you menses, you might be to consult your gynecologist. But its not unusual to observe delays in periods when pills are used. Thanks and best regards, Luchuo, MD.