What happens when I'm on the shot?

Korah • Hey, I`m 16 years old and bisexual. I want a medium sized family, 3.5 kids and a dog, ya know? I plan on being an OBGYN.
I'm on the shot and I don't have my period, but <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> keeps asking me if I've started my new period.