So confused

My breast started hurting a week before my period. My period normally last 4 days and is super heavy. I started to bleed on the day that it was due, but it was brown to start and then changed to a brighter red but very light and only lasted 1.5 days. My breast are still very sore and feel swollen. I took a pregnancy test but it said negative. Is there a chance that I could be pregnant and it’s just to early to tell? Or was it just a weird cycle?

Thanks