4 days late on my period


i am currently 4 days late on my period had really sore boobs yesterday and have been extremely constipated. i took a pregnancy test and it came back negative , tonight i went pee and noticed when i wiped that it was pink . it’s very light i can post a picture, and it’s only when i wipe . any advice on what i should do? or if it’s my period or not . my periods are NEVER late, i track them with a app on my phone.