I Really Thought This Month Id B Pregnant, My Boyfriend

i really thought this month id b pregnant, my boyfriend and i had unprotected sex on the day i ovulated and i wasn't suppose to get my period until the 12th but i started bleeding today. i don't know if it implantation bleeding or if my period just came early. i took a test but it came out negative and i don't know if its due to me testing while bleeding?