Why Cant I get pregnant?!

This is so frustrating! After having a miscarriage is July 2014, all I've wanted was to be pregnant again! We weren't even trying the first time and now that we are, I can't get pregnant! I know I'm not the only one! Every month I think it's "my month" because of one symptom or another. I've tried  BDing every other day, Preseed, ovulation tests, "not trying"....blah blah blah. Does anyone have any advice for me? Or feels the same way??