I made out with my boyfriend. We went up till the the third base. I however can't recall if he touched my vagina after he had cummed. I took a pill anyway. I got my periods after a few days. But the flow was very low. And it was brownish. My friend suggested it could be staining. But it went on for four days. And eventually it did turn red. Is there a possibility that I could be pregnant? Were they actually my periods or mere staining? Please help. I am really worried!