Why can't i concieve?😣

America
My Dr. Told me I have a very healthy uterus and that I do ovulate..I've had many chances of getting pregnant, but it just doesn't happen! I'm irregular and sometimes I skip my period. I havnt gotten my period since January! I have taken 2 test and they both were a BFN :( What am I doing wrong ? What can I take to get pregnant? I'm getting frustrated:/