I haven't had my period in a month and a half. i used a condom the last time i had intercourse. took a pregnancy test and it came out negative.

Some thoughts...: In a woman with regular periods, some causes of a late period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (like birth control pills), hormonal imbalances, etc… Seeing a doctor is a good idea if symptoms are persistent or worrisome. Pregnancy can be a cause of a missed period, but unlikely with negative test.