what could this be?

I’m 22 and never in my life has this happened i’m never irregular with periods and if I am it’s by a few days. My period is 15 days late according to glow. And about 4 days ago, I went pee wiped and saw light blood and went again and NEVER saw it again. My boobs have been sore this whole month just like my period. And me and my boyfriend been TTC for two years i never got pregnant before so I kind of am pessimistic about me being pregnant. Any thoughts what could it be? Again the blood was very light and never came back. Any one had this happen before? I’m over two weeks late. I do feel sick at times as well.