Making the switch from birth control to HRT this week!

I wish there was a “clueless” flair. I have been on birth control mainly as migraine management and am making the switch to HRT. Picking up the extra gen patch and Prog cream today! Doctor said to just make the switch, no need to wait to do it. I’m wondering what to expect. How do periods happen if the hormones are the same all month long? I still have mine. Thank you for sharing about any shared experience.