Progesterone level

So I miscarried back in November but altogether my husband and I have been trying to conceive for over a year. Ovulation for me is getting later (day 17/18) and periods are coming much sooner (cd 25/26) My doctor ordered a 21 day progesterone blood draw and it is 0.4 ng/mL. What does this mean? I don’t go back until 2 more weeks. Thanks in advance!