I am mostly male, but feeling both male and female. And I have monthly periods.
(Thanks to my mom's genes, I often get migraines during my periods...)
Then again, I have extreme amounts of both male and female hormones surging through my veins, so.. That would explain the periods.
I'm not on HRT, I'm not in any way transitioning, and my breast size is a very, extremely small A. (Meaning: Near to nothing, but at least something. It actually looks as if my chest muscles are huge. Which they aren't; it's all soft and such.)