Missed period

Hey ladies happy new year I need some women advice . So me and my man were having intercourse one morning and after we were done he had some light brown blood on his shirt I suppose and this was in December around the 4th or so when I went to go clean myself off and I Wiped my self it was honestly a light pink brown blood that lasted like 3 days I used panty liners and all but no blood on it only when I wiped myself it just showed a light pink on the tissue paper ? Do I count that as my period ?? I do track my cycle on this app and I do go off the ovulation days to try to convince but I haven’t started a true period yet and now it’s the beginning of the new year 3 days in and the app saying I’m 16 days late and I have took pregnancy test they say no so I’m confused ! Advice advice advice please