Natural Progesterone

JM
I've had two miscarriages in the past year. The last one I was on 200mg of the synthetic progesterone pill. It didn't help, my levels were still low. Does anyone use a natural progesterone? If so what brand and does my doctor have to proscribe it or can I buy it online or in a store? I've heard of some creams with wild yam are suppose to be very similar to your body's own natural progesterone. Thanks for your help!