If you had your period on the 28th of last month, it is normal to have your period on the 21st of the next month to the 3rd of the next month if it is regular. Normal menstruation is from 21 days to 35 days, the average is 28 days, the period is within 3~7 days, early or delayed within 7 days, the amount of menstruation is between 20-60ml is normal. Some people may have different menstrual cycles due to their physical condition, environment, living habits and heredity, etc. Generally speaking, if menstruation is delayed for 7-10 days, it is recommended to go to the gynecology department of the hospital to rule out the possibility of pregnancy and other gynecological diseases. Menstruation is affected by the environment, mood, diet, tension, sleep, etc., so it is normal for it to be advanced or delayed by no more than seven days. If you have abnormal menstruation, go to the hospital in time for further treatment under the guidance of a professional doctor.