Please help

Sky
I came off b/c in November and had a regular period and then also in December and January and February! This month my period is late. Almost a week and there isn't any sign of it coming! I took to pregnancy test and both were negative! I did start working out this month, could that have something to do with it? My S/O and I did the deed the other night and it hurt! I am just confused! Please someone help