I'm in a very similar situation - spotting early for the last 6 months or so. My progesterone was 7.4 and my OB said it was on the lower side of normal. Her solution was Clomid (unmonitored and without further testing other than an SA). Instead I went to an RE and I'm in the midst of the testing now. So my OB did not see any value in prescribing progesterone supplements and instead said the treatment would be Clomid.