ICT POSITIVE IN SECOND PREGNANCY. Now?

Sir/Mam, I am 27th week pregnant. My blood group is O negative and my husband's blood group is A positive. Previously I had a miscarriage. The miscarriage was spontaneous. I had mild spotting that time for around 15 days and ultrasound report was okay. But after 15 days, the heartbeat of the fetus was absent. It happened when the pregnancy was at 9 weeks. The doctor did D &E and within 24hrs one anti d injection was given to me. After one year, I am pregnant again. And the doctor did not give me any ict test. In the 5th month of this pregnancy, as my trisomy 21 screening was positive, I had to do amniocentesis and the doctor gave me 300 mcg anti d shot that day. After 5 weeks of that anti d shot, I tested ict , and it came positive. Is it for this injection? Or there is a chance of immunization for the previous pregnancy? What should I do now?