Depo shot.

So I got the depo shot, on the 16th of this month. It's been almost 20 days since I've had it, I haven't had a period this month and I'm now two days late according to <a href="">Eve</a>. I thought I was supposed to have a period? I'm not getting the second shot I've had such a awful headache that just keeps coming back because of this shot! All I wanna do is eat and I'm so moody. But anyways sorry for all the rambling I just need to know if anyone had the shot and had a period or periods.