Missing Period

Me
Okay, so, to start off my periods have always been extremely irregular so I'm hoping that that might have something to do with all of this.
My period started in January around the 25th or so. Then, in February, it came early around the 13th or 14th which I'm attributing that to me changing my diet and working out regularly again.
So now, in March, I haven't gotten my period at all. I was expecting it around the 15th or so and it never happened. Then, on the 22nd, I had some light spotting but it went away after a day. 
I took a total of 3 pregnancy tests: 1 was positive and the other 2 were negative. I'm not really sure how to interpret all of this and I'm not sure what's going on with my body.
Any insight or advice would be appreciated!