So confused

I was supposed to start my period 4 days ago...I have been going by what the glow app says and it's usually pretty accurate with my days. I log every day and we'll I didn't start my time so I was excited. Than I took not 1 not 2 but 6 pregnancy tests (yes I know how crazy that sounds) but they all came back negative. Now all I can think is what is my body doing...