How To Determine If I Had A Miscarriage?

My period came 4 days early and on the third day I dropped what looked distinctly like a 1cm sized foetus. I didn t know I was pregnant but did the math and it all lined up. Other than breasts getting bigger and fatigue I haven t experienced any other symptoms. I went to the doctor and they agreed it looked like a miscarriage and took some blood. My hgc level was 0.6 though, and to be pregnant they said it had to be above 5. So they said it wouldve been a decidual cast. I have a few issues with this. It didn t look like a uterus shape. It was small. It had what I could make out as eyes, hands and legs. I m not going crazy. My bleeding is slightly heavier than normal and I m having pretty bad cramps. I never have cramps and it s now 4th day of my period and the blood flow is actually heavier than it was initially. Usually by the 4th day it s all clear. So my question is: is it possible to have had the miscarriage a few weeks back but the foetus didn t expells till now, and therefore my hgc levels have returned to almost normal? Or is this just a really weird case for a decidual cast?