Im only 16 so a bit confused im over two weeks late i bedded 5 days after my period and this app said i was fertile about 4 days after im getting frequent headaches&back pain and had like period pain around the time i was due to come on but felt worse still no sign of my period and i do have sore boobdls can anyone help please& i did take a pregnancy test around the time i was due on but late at night and it was negative? Sorry if i sound silly.