Hi Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern... Delayed periods could be because of many problems such as hormonal imbalance, excessive weight gain, getting pregnant, excessive stress & other factors. If you had unprotected sexual intercourse since your last menstrual period & your periods were regular previously, getting pregnancy is most common cause of delayed periods in that case. A urine pregnancy test such as HPT can be false negative in early part of pregnancy. This is due to less HCG hormone in urine which is normally used to check pregnancy. A repeat pregnancy test is advised after a week, if you still has your periods delayed. Refer to a gynaecologist Hope this information helps