Ttc #4 remarried

Hi I'm new here . I have 3 kids already but I'm newly remarried. We have been trying for several months and nothing. Is it different with a different partner? Could it be me ??? I'm getting pretty discouraged . He and his ex wife 7years ago got pregnant and she miscarried at 4 months but she had n affair so I can't even say if the baby was his. I guess I need some relief to relax any advice on what to do . Should I try a supplement for him or me besides my prenatal?? Anyway I am supposed to start on the 11th and I'm not feeling anything but some mild cramps.