Weird bleeding when period is due, could I be pregnant?

I had unprotected sex 3 times on July 26th, no ejaculation fully inside except from finger touching slightly. On August 15th, we also had unprotected sex again. And used pull out method then too, no ejaculation inside. This month [August]I haven't had my period. I am not on birth control abd have some sumptoms. On the last day of when my period calendar said I'd have my period - the 31st, I had light brown spotting - size of a quarter and extremely light and when I wipe it's pink - sometimes nothing. This has been going on for almost 2-3 days. Light cramps, nothing like my period. Could this be implantation bleeding after it was due? Could I be pregnant? I haven't tested yet..