Femara & progesterone? HELP

✨sparkle🐠cubs™️✨ • Twin Momma, 🚨💉💊, married to my best friend, ALLY & bleeding heart liberal!
So, I am supposed to be starting Femara for the first time this next cycle as well as progesterone suppliment as my levels have been running low. Everyone I have seen doing this combo uses progesterone suppositories, but my doc wrote for the oral pills for cd16-20. Has anyone else taken this combo, & if so, what was your schedule & regimen? If I stop the progesterone cd20, wont that trigger my cycle? 
Any advice or input is greatly appreciated! This is the only place I can ask questions like this, so please help if you can!