Don't know whether to take progesterone

Previously Adam and I have had a couple of tests come back positive but they have never held. When the last one didn't my ob did a progesterone level and said it was low. He then wrote me a script for progesterone and said to take it when I got pregnant again after I had a level drawn. I had my level drawn yesterday and asked his office if I should take it or not and they said they would check with them. I never heard from them. I then emailed him last night and he asked me a couple of questions but the still hasn't told me what to do. Gah!!!!