Abnormal cycle

Caressa
My period was about 2 to 3 days early last month and it was very short. I usually have a 6 day period but it was on for 2 days then spotted on and off for another day. Now 15 days later im bleeding again. Smh idk whats wrong I took 2 home pregnancy test about 1 and a half weeks ago but they were negative. Has this happened to anyone before?