I am 18 and the other day I put a condom on a banana and masturbated to climax. Afterward, the condom had a little blood on it, brownish-red, like my period. I was relieved, thinking I got my period (though it would have been a few days earlier) because I have had unprotected sex 3 times this month and I am not on the pill (but he never came inside me, always outside.) However, for the past three days I've been bleeding lightly: less than a period, but it seems like more than regular "spotting" or possible "implantation bleeding". I know it could be an early sign I'm pregnant, I could have cut myself while masturbating, or it could be a very light period. Which is the most likely?

Also, when should I take a pregnancy test? My period is due this week and the bleeding seems to have stopped for the most part after 3 days. I am very nervous.