Progesterone suppository's and spotting?

I am around 5 weeks. My HCG has been doubling perfectly but my progesterone is very very low. My doctor prescribed me the yellow pill form of progesterone 200mg, I take it vaginally at bedtime only everyday.. Did anyone else have to take this and does it help?? I had a MC last February so I'm worried I may go through yet another since my progesterone is super low...