Croydon-My second mc my progesterone was very low, I think 3 the first time, 4 the second time, and 3 the third time. My hcg was rising normally but my RE told me that with progesterone that low that my chance of miscarriage was high, especially since I was already on progesterone suppositories from the time of ovulation so it must have just been a nonviable pregnancy. Since you are not already on progesterone, I would say that it's worth a shot. I have heard stories of girls with very low progesterone who started the prog suppositories and it made a huge difference. For me, I was already on them and prog was that low so my situation was different from yours. I say it can't hurt!
Sending prayers your way.
Erin