Brown Discharge...ANSWERS ??

So, my period was supposed to come February 13.  That day I had watery discharge with a light red tint and I put in a tampon. At the end of the day I took it out and it was only a streak of brown blood. So I counted it as late. Then me and my partner had sex with protection, not sure when but, on the 21st we did it with no protection. He used the withdrawn method...works normally, so he didn't ejaculate inside me. Since then I have not had a period, took a test...it was negative. and lately I been having brown discharge in the beginning of March for like 2 days...mind you, my period is due on the 14th. My cervix is high, open, and soft...what's going on ?  Oh and then each time he's fingered me lately my cum/discharge is like brown blood. As of March 9th I got more brown discharge the day after taking the test . I have been gaining weight, a little stressed, and a lot has changed. Could I be pushing my period back with the stress or is the stress causing these 1-2 day bleedings ? PLEASE HELP