Miscarriage?

Started bleeding around 1030 pm went to the er around 4pm the following day. I had passed a few chunks of tissue one aprox. 3 inches long rectangular in shape but the bleeding was mostly moderate and only once or twice was it really red aside from that it was pink or brownish. All of my blood and urine came back good but they found no sign of a baby after doing sonograms. They told me I must have already fully miscarried I'm still spotting a little one day later but it just doesn't feel like enough blood for a miscarraige, any insight?