Hcg level after miscarriage

As some of you may know I miscarried on 2/26/18 and I was wonder about hcg levels

On 2/23 my hcg was 183 (5 weeks and 2 days)

On 2/28 -my hcg was 74.8 (2 days after miscarriage)

Today 3/14 my hcg level is 69.8 ( 2 weeks and 2 days after miscarriage)

My dr said it should have went to zero by now because my levels were low and sending me in a week for more blood work and a ultrasound and said their maybe a chance I got pregnant right away because your levels don’t have to be at 0 to get pregnant again

Anyone else go through this???

How long did it take ur hcg levels to drop??