Help!

So I've been on birth control only for 3 weeks. And since then I have had unprotected sex 3 times( I know,
​Not very smart.) but he finished outside 2 time and finished inside 1 time.) and I have forgotten to take my pill a couple times and messed up the times. And I am not supposed to get my period for 2 more months, but I have randomly started bleeding today, and it's too much to be spotting, but too little to be my normal period... Does anyone know what's going on with me?...