Bleeding and Clotting No Other Symptoms

So I thought I was 13 weeks pregnant by my last period, but I started bleeding a little bit on Wednesday. I called my OB and they said keep an eye on it and keep them updated so I did. Friday the bleeding got a tiny bit heavier, had to wear a panty liner, and I had some small clots. Called my OB they said stay off my feet. Rest. Dont lift. If it got worse call them. Well yesterday it got worse, clots were getting bigger had more blood. It filled up a pad but it took 6 hours. Still worried me, I have health problems anyways. So I went to the ER and they did an ultrasound and bloodwork. Said that my HCG levels was 670, and they didnt see anything in my uterus; which could mean I'm either earlier on than we thought or I already miscarried and passed the baby. Now that I'm home I'm barely bleeding at all. No clots at all. I gotta go back Monday to test my HCG levels to determine if I'm early or if I miscarried. Anyone else have a similar story? Please share anything. I feel like if it was a miscarriage I'd be in pain. Have more symptoms than just bleeding.