Delayed menstruation and enlarged nipples are considered the most likely cause of pregnancy. Because after pregnancy, estrogen and prolactin increase relatively, which will cause breast development and nipple enlargement. It is suggested that you can use early pregnancy test paper to test yourself, or go to the hospital to draw blood for human chorionic gonadotropin, which can clearly diagnose whether you are pregnant or not. If menstruation is delayed for more than 10 days, ultrasound can be done to see whether it is intrauterine pregnancy or ectopic pregnancy. If there is no pregnancy, you can observe for the time being to see the thickness of the lining of the uterus, which will help you to estimate when your period will come, and if necessary, you can use medication to encourage the onset of menstruation. If you are not pregnant, consider that it may be endocrine disorders, hormonal stimulation caused by nipple enlargement.