Prometrium 200 mg orally

I am 6w5d pregnant with my 2nd rainbow baby. I had a m/c in July of this year. Dr had my hcg and progesterone levels checked... Hcg is 14889 and progesterone is at 9.2 so she prescribed a supplement to be taken orally. I read vaginally is much more effective. Anyone had any experience with this medication??? Did it work for you??? Which is the more effective way to take it to help raise levels???