low progesterone in early pregnancy

I'm currently 4w1d pregnant. When I got my blood test 13 dpo they said my HCG was great at 145 but progesterone was low at 14.1. I was on 100mg progesterone suppositories 2x daily starting right after ovulation. They upped it to 200mg 2x daily after getting my blood test results. I just went in for another blood test (it's 48 hours later) and am waiting on the results. Should I be worried? Should the increase in dosage help? What kind of levels do you need to sustain a pregnancy? Thanks!