May baby now is April baby

Hello girls, someone explain to me when I was able to get pregnant, I am now 16 weeks and 4 days pregnant. It has happened to some of you. I have a regular period. My cycles are from 25 to 26 days. My last period was on August 17 and my first ultrasound was when I was 6 weeks pregnant. when we are in the ultrasound I have a baby of 11 weeks and two. I was shocked because I did not expect my baby to be so big. Thanks, everything is going well with the pregnancy. I don't know why I had my normal periods in June July and August. I don't know when I got pregnant. Well, I have to take me by the date of the ultrasound. girls leave your comments experiences thanks.