My period started on August 5th, and I had sex every two or three days starting from the day after the 12th. By the 20th, I felt so tight in my chest, so tired, and had abdominal pain all the time. I want to sleep. I took a test on September 5th and found no pregnancy. I took another test on the 12th and found no pregnancy. I also took a test on the 15th and it was all blank. What’s going on? I feel very much like I’m pregnant, but it’s all blank. What’s going on? .

Friends please help me analyze it, thank you very much!