Late again but still negative

Reggie
Second month in a row my wife is late, but negative pregnancy test. She is never late, and she took clomid too. She also missed a very important lab appointment to check her labs after taking clomid, I am a little frustrated because she's usually at top of these things, but was extremely careless this month. We both want a child really bad, but this month she put in very little effort in trying to get pregnant. Now she is two days late and we don't know if her progesterone levels are too low to implant. In the past I have pressured her which I regret. But we have no idea what is going on because she is very regular, and not stressed one bit because both of our lives are very happy. Ladies, what are your thoughts?