hi welcome to H.C.M.Forum. for infertility
there are several causes. hypo thyroidism, polyps also can cause failure of conception. as both of you are normal invitro fertilisation
can be tried. with your egg& your husbends semen. next step is home measures. have sex between 11th to 20th day of cycle absconding between 1to 10 & 21 to 30th days. follow male above mode of sex. dont get up or wash immediately after sex. wishing a beautifull baby soon.