recurrent miscarriage

I found out that I am a FVL (heterozygous) six months ago after a history of seven unexplained miscarriages all over seven years of marriage. I had two spontaneous pregnancies, four insemination and one in vitro fertilization ( 2 embryos) ,all ended with miscarriage as early as 5 weeks (8 weeks at most). In my eighth pregnancy (miscarried a month ago) I had heparin shots twice a day ( clexane 0.2 -2000UI anti-Xa) plus baby aspirin and I lost the fetus in 5 weeks. Was it the appropriate dose or it must be reconsidered? I am 1.63 m high and weigh 60 kg if it is calculated according to weight! I am negative for the following lab tests: (Anti-cadriolipin IgM & IgG / Anti- phospholipid IgM & IgG / ANA & ANF / Lupus Anti coagulant). My INR is (1.1) and PT is 29.8 sec and The prothrombin activity is 88%. I've never developed a clot; the FVL  complications only appeared during pregnancy!

Shall I try to conceive again? Can you tell me please, what is the appropriate heparin dose that helps me to maintain pregnancy?
What if my husband and I have identical HLA test, does that mean the impossibility of having a baby? ( we haven't had this test yet)

I really need an answer please! I'm suffering real depression!