21day progesterone check

My Dr. Is insisting on doing a 21 day progesterone check but I want to start my progesterone suppositories 3dpo. Will this mess up my progesterone test? She wants to make sure the dosage is enough at 50mg of clomid but obviously they are because I just got pregnant last cycle on 50mg. I don't want to waste this month and I know I need the progesterone suppositories to have a chance at a healthy pregnancy. What do you guys think? My doctor also doesn't believe in progesterone helping anything at all. She said it's not proven to help unless someone is actually pregnant but she prescribed them just because I begged her. The month I took them was the month I got pregnant but ended in a miscarriage...

Please help any advice would be greatly appreciated!