Depo troubles

Okay, so I am 19 and have been on the depo shot since November 2014. And have always stayed up on them. I only had my period once in each round, both lasting a week and a half, and never having any mood swings or other troubles. This last shot, however, has cause issues. I started spotting in the beginning but stopped. I got my period on may 20, and it hasn't stopped. I am moody to the point my bf won't say anything in fear of me snapping at him, I can cry at the drop of a hat, then it turns to laughing. I'm having severe headaches where I can't wear my glasses, and I'm nauseated all the time. I've taken two pregnancies tests and they were both negative. I talked to the nurse and she just blew me off saying it's normal for depo. I'm worried that it is more...any suggestions?