Hi I'm 16 And Me And My Boyfriend Had Unprotected

Hi I'm 16 and me and my boyfriend had unprotected sex . And he says that he didnt use the pull out method fats enough. I was with him saturday morning and today's Sunday and my periods supposed to start, is it possible that I am pregnat? I'm slightly bleeding a brownish color and I feel a little pain in my stomach. Does that mean I'm pregant? Is it to early to tell!? I need advice please