I Had A Miscarriage Around 3 Weeks Ago. I Only

I had a miscarriage around 3 weeks ago. I only have heavy bleeding for a day which was the day the sack came out. I was around 5 or 6 weeks pregnant. I haven't had much pain or anything and my doctor told me I didn't really need to get a d&c. Bleeding has not stopped but it's not heavy. I was wondering if that's normal since its been 3 weeks. My hcg is at 600 and has been dropping around 100 every week. I just need to know since I'm having a natural miscarriage if it's normal for it to take long