I am 22 year old female. This month I am two days late for my period. Last month my period was strange. It was only brown tissue that barely came out and it lasted five days. My period before that was perfectly fine. I am sexually active and have already taken a pregnancy test that stated I was not pregnant. I also have irregular periods but what I am wondering is if it is normal to go from a regular period to brown tissue to nothing?

Help please anybody