I need some clarification...

So I just got my period. I think. I'm on birth control but I only started it a few months ago. If this is my period it's pretty light. It's also a dark red/brown so I know that's just old blood. I've heard that because I'm on birth control this technically isn't my real period. So does this mean I'm not pregnant? I've been waiting for it to come to see if I should take a test or not. I'm just curious because I'm wondering if I should still take a pregnancy test or if this means I'm probably not pregnant. Sorry for the dumb question... no rude comments pretty please. Thanks ladies :)