late period

My period is four days late and I've been feeling weird lately. I got my depo shot on December 3rd. I had brown discharge last week, started on thursday and ended Sunday. I'm having all period symptoms but no period. Besides getting cramps and sore boobs here and there. I've never had those during my period. I took a pregnancy test Saturday morning and it was negative so I'm not sure if it's just the depo shot 🤷🏼‍♀️