Hello, and I hope I can help you today. Pregnancy symptoms vary widely between women, and the symptoms of irregular hormones (which can also delay your period) are very similar to the symptoms of pregnancy. Women sometimes don t ovulate at the same time as usual, and other factors, such as weight changes, travel, and stress, can also make your cycle abnormal. Furthermore, in your particular case, your husband has been sterilized. And you had a pregnancy test that was negative, which is just as accurate as the ones in a doctor s office. So I think you do not have to worry about being pregnant. To be totally secure about your husband s sterility, he could get a sperm count done to make sure the vasectomy worked, if you would find that reassuring. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown