Delayed miscarriage-need answers please

Hi, I had a miscariage last year and I've been trying to find out what happened and why it's so different from all the other heartbreaking stories I've read.  I had in an IUD and didn't realize that I was pregnant since I had no periods to miss and had no early symptoms. My IUD fell out when I was on the toilet (I felt it and then saw it in the toilet) and about a minute later I started feeling horrible cramping and about two minutes later I passed the fetus still in the sac that was attached to a sort of big blood/tissue clot. There was no blood, no other clots and the everything was dry and stiff looking (sorry for how graphic this is). I went to the doctor and they said my pregnancy hormones were very low and that by what I described the fetus was about 10 weeks old. He said it was a delayed miscarriage but couldn't tell me how long it had been since the pregnancy ended, just 'a long time since there was no blood or symptoms'.

Was it the IUD that kept everything in and delayed it? How long was it in me for it to have come out like that? I really need answers because it's driving me crazy not knowing when I got pregnant or how long until the miscarriage actually happened.  Anything would help. Thank you