Help please

How do I know when I’ve finally miscarried? Last Saturday I got my bfp only to begin spotting that night. Sunday the pink spotting turned bright red and we went to the ER they did a transvaginal ultrasound but said it was too early to see anything. They did an blood test and my hcg was 667. They told me I had a UTI and sent me home with antibiotics and told me to come back 2 days later. I went back on Tuesday and my they did more blood work and my levels dropped from 667 to 440. They told me I was miscarrying and sent me home. Yesterday I had an appointment with my OB and she didn’t do anything. She didn’t do a transvaginal ultrasound she didn’t check my blood levels again to be sure. She pulled up my last report from the ER and said my levels dropping was a sure indication of a miscarriage. They she sent me home and said it would happen on its own. My question is how long after a drop in hcg did you miscarrying naturally. I haven’t had any cramping just light spotting not enough to fill a pad a day. It’s been 4 days since my levels dropped? I know after I miscarry I will bleed for weeks but how long does it take to actually miscarry? I hate this wait.