Low progesterone success stories?

Alright, after two failed iuis, I managed to ovulate on my own. Some kind of magic clearly happened, because after nearly 2 weeks of PMS symptoms, I went back to my RE with the intention of being cleared to induce a period. Instead they called back and said I was pregnant and had a good HCG number, but my progesterone was low. So now I'm starting progesterone suppositories tonight, but I'm worried. Has anyone successfully sustained a pregnancy that had low progesterone in the beginning?