Recurrent Miscarriage in beforr 6th week

I had  3 miscarriages in past 2 years. 1st miscarriage - pregnancy kit positive and beta hcg is 35. Then got bleeding on 33rd day. Doctor said its a miscarriage. Then 1 month later i did a scan and came to know missed product is inside uterus then we did beta hcg its 500. Then doctor gave abosrtion pills to clean the utreus. 2nd miscarriage - 35th day bleeding happened. Its an ectopic pregnancy. After a month only we did a scan and know about its an ectopic. 3rd miscarriage - 40 th day bleeding happened. Beta hcg was 45 then after a week it reduced to 8. We did all neccassary tests. Amh ,Karyotyping ,Lupus anticoagulant , sperm DNA fragmentation, antibodies test like IgG,IgM, rubella,3D ultra sound - all are good My blood group is B du positive. They considered as B negative(see attachment). After a second miscarriage, doctor suggested Anti d injection also. She said unexplained RPL. Could you please help to finad a reason and solution for this, is there any test i missed?