I haven't gotten my period !!

Ok so I'm supposed to get my period today. Monday I used the bathroom went to wipe had a lot of fresh red blood so I thought I started it .. nope it went away right after that .... comes Thursday I went to use the bathroom .. same thing a lot of blood when I wiped and even some coming down in the toilet thought I started it ... nope it went away I took a pregnancy test just rule out the pregnancy it came out negative  so if I'm not pregnant what's going on !!! I'm freaking out I need some advice