Super stressed ! Help please

I just got off my period on the 12th and I had unprotected sex the 13th or 14th and I'm super scared because he said he doesn't know if he cam inside me. I know that he didn't pull out. I'm so stressed bout it. I feel so guilty because I didn't want to have sex with him ever again and it happened. I feel so nasty. I feel like I let myself down. I told myself I wouldn't hangout with him ever again and I did. Also I was wondering if he drinks and does cocaine a lot does that make it harder to get someone pregnant?