Frustrated ttc

I am 29 and have 3 live births and never had a problem trying to conceive before but now that I truly want to have a baby I cannot seem to get pregnant. I had a miscarriage and before ttc. Me and my other half have been trying for over 1 1/2 and since the miscarriage and nothing. We tried p.n.v and I went to the Doctors and everything normal and he did to