So confused

According to my lmp I was supposed to be 7 weeks. I went in for an ultrasound last Thursday and they couldn’t find anything not even a gestational sack. The doctor sent me to do blood work and my hcg came back at 300. On Friday I started cramping a lot and spotting and then bleeding and I passed some tissue. But I only bled for one day is that normal? Today I went to get more blood work done and I will get it back in two days. I’m so confused but I think I did miscarry. Is bleeding for only one day normal when you miscarry?