which would include the following:-
Thyroid (TSH betwen 1 and 2 optimum. T3, T4 and antithyroid antibodies)
Clotting screen (Factor V Leiden, Antiphospholipid syndrome, anticardiolipins, MTHFR, prothrombin gene mutation etc etc)
Uterine - up to date hysteroscopy
Infection for you and DH
Autoimmune issues (lupus anticoagulant, Rheumatoid factor, antinuclear antibodies etc)
Immune issues e.g. NK cells, Tnfa etc (more unusual and needs specialist to test)
I see from your other post you were on heparin for first pg. Did you use it this time round?
Clearly you may just have bad luck this time round sadly and hopefully next time will be the lucky one for you. However, GP may run some of the above?
Best of luck,