Pregnancy day 11 should mean 11 days after intercourse, which can usually be detected, but it is better to test around 16 days. Around 7 days after intercourse, the fertilized egg is laid and can start to secrete HCG, and the HCG in the blood and urine of pregnant women starts to rise, which can be detected by early pregnancy test paper and blood HCG test. When using test strips to test yourself, you need to pay attention to the use of morning urine, soak one end of the test strip in urine according to the instructions of the test strip and take it out after 2-3 minutes to observe the result. If one red line appears, it means negative, which means no pregnancy, and if two red lines appear, it is positive, which means pregnancy. However, there is a possibility of false positives on the early pregnancy test and further tests need to be performed in the hospital. If the blood and urine test is positive, you can basically be sure that you are pregnant, but you need to wait for another week to go to the hospital for a blood test for HCG level and ultrasound to confirm whether it is an intrauterine pregnancy and to exclude ectopic pregnancy and trophoblastic disease.