possible pregnancy

OK so right now I'm a bit nervous. .OK so I had intercourse on a Sunday and my period was due 3 days later but instead of my period I got a brown stain that only appeared when I wiped for 2 days this happened then on the third day I got this huge amount of blood stain but it went away right away..I took 3 pregnancy test 2 on the same day 1 today at the doctors..my question is can I be pregnant or something else...

p.s we used with drawl as birth control..