You can get your period while taking progesterone if the dose is low enough. When I was taking 200 mg progesterone (prometrium) and was not pregnant, I got my period w/out stopping the progesterone. Same thing when I was on Crinone 90 mg. When I was on 400 mg suppositories I did not get my period even though I wasn't pregnant. I had to stop the suppositories to get my period. So it depends on the dose...
the first day on it but didn't get my period. My RE said the prog suppositories can delay your period. I went off of the progesterone 15 days past IUI and my period started the next day. I hope you have better results! Keep us posted!