Old thread, but thought I'd chime in, since I went on BC for the same reason. Since I wasn't out completely at the time, I used the excuse that I felt like my cycle was too heavy and too long (for reference, I was using super-plus or ultra tampons and my cycle lasted almost a week), and my mom nor my OBGYN thought anything of it. You're not lying, nor is it unreasonable. Since, my cycles have been fairly light and only a few days long, and have significantly decreased my dysphoria. My cycles never went away completely because of how bad they were before, but it's way better than it was before.