Questions after miscarriage

I had a miscarriage back at the end of april. I had bleed for about 3 weeks. Seen the doctor and told him what happened the night after our appointment and that i heard a plop and there was a lot of blood. I thought we were good and that my body cleaned me out. I haven’t had a period up untill the 6th of this month. I had passed a brownish tissue and am assuming that was the sac that the baby was in. Now it lasted till the 19th. I had blood work done before this and my levels were down to 10. Is this normal? Was it my period or just cleaning out?