Pregnancy terminated without a miscarriage

I was wondering if anyone had any information for me. On September 23, I took a home pregnancy test which was positive. I went to my obgyn on October 1st and took a blood test which was positive. My first appointment was on October 23, but I was told it was too early to do a sonogram. My doctor did an internal and said everything was fine. I did find a little blood in my urine November 19th, but I was not too concern. The next day was my next visit, and the doctor did a sonogram and said she saw the heartbeat. I had my first trimester screening the next day on November 21st, and I was told there was no baby.

I am not sure what happened. The specialist explained she believes I was pregnant early, but the baby never developed. It was like the cells of the baby just disappeared and dissolved in my body. Obviously, my doctor did not see a baby because the specialist said according to the dates, I should have been 12 weeks pregnant. There was no traces of a baby in my uterus sack. The sack actually looked like it was collapsing. I had no cramping, back pains, or heavy bleeding.

Does anyone have any information? Did I have a miscarriage or was it something else? I am confused and worried