frustrated and confused

Ok so I haven't had a period in a month. I'm going through all these insane mood swings, waves of extreme hunger, nausea, I'm tired a lot, I feel bloated and recently find it a little difficult to go upstairs without blfeeling out of breath. I've taken three tests and all have been negative. June 28th, 2016 I got my first dose of the depo shot. September 29th, 2016 I was supposed to get a second shot but didn't go. My man and I are trying for a baby. With all that said should I keep testing or go to a doctor and figure out what's going on?