Waiting for a miscarriage

This is torcher. So baby didn't develop and I'm waiting to pass a 1.5 cm sac. Dr wants my body to try and miscarry naturally. She said there's a chance my body would just reabsorb it, but how am I supposed to know if that happens? I've been cramping off and on the last couple days. Nothing major just the feeling my period is coming, but absolutely no spotting. I just don't know what to expect and it's killing me.