Luteal phase length and progesterone cream

Just found out after deligently charting for the first month that my luteal phase is only 9-10 days long. I am waiting for blood work results to see if there is an underlying thyroid problem, but I have also ordered progesterone cream to try and lengthen my luteal phase. Has anyone had success with this? Also, did you continue to use it once pregnant to help prevent miscarriage, and if so, for how long? Thanks everyone!