Trying to get pregnant. It harm baby?

Hi doc, I had my LMP on 22nd jan. I had mild spotting on 20th, 21st jan . I tried testing with ovalution strips yesterday it showed LH surge for me, which is 11th day from LMP ( full flow ), but I had spotting for two days before that . We had relations on day 9 and 11 as well as 11 showed LH surge . I have a question whether I have to consider it as 11 day or 13th as I had spotting for two days before my period . When I consulted a doc online she prescribed me ovalution induction and progesterone support medication, I did not took induction medication as it's primary used for breast cancer treatment and I know I'm ovaluting as per scan sometime back . I am trying pregnancy for three months but period is coming regular . Do I need to take progesterone support medication duphaston tablet from day 16 mentioned by doc ? Will it harm baby ?