I went to the doctor because my period was irregular and now it is about 3 weeks late. Today I went to the doctor for an ultrasound and the results showed that the uterus was tilted forward 38mm, the endometrium was 21mm, and the uterus had a 4mm echo structure. The doctor told me that there was a 70% chance of pregnancy. After that, I had a beta HCG blood test and the doctor said I was not pregnant. So, doctor, can you tell me what is the meaning of a late period and an empty echo mass in the uterus? Thank you, doctor.