Progesterone and late periods vs pregnancy

Hello ladies! So Im 18 days past IUI, havent gotten my period and got a BFN testing at home. At 2 days late for my period I called the dr & told her I got a BFN, no period and should I still be taking the progesterone suppositories. She said yes and to test a couple days later. Well now Im 5 days late and Im reading a bunch of things online about ppl not having started their period till after they stopped taking progesterone. What have yalls stories or experiences been with progesterone and pregnancy or AF coming or not coming? This is super frustrating (as yall know).