Feeling guilty for not reporting

I think I was possibly drugged and raped by a stranger a few weeks ago. The last thing I remember is talking to him in a bar after drinking significantly less than I am used to, and I woke up undressed and alone in my own apartment. My roommate said she heard us come in around 3am and have sex at least twice. I didn't even know his name.

I looked for proof that we had sex, condom wrappers, anything. There was nothing. It was like he purposely left without a single trace of being there. If my roommate hadn't told me what happened I would have had no idea.

I was so freaked out that I immediately just showered and went back to sleep for the whole day. I know this was a mistake and that I should've gone to the hospital. Weeks later, I feel so guilty about not doing that. He could be doing this to other girls. If I tried to report it now, I know how it would look. There's no physical evidence left besides a few faint bruises. I don't even know the guys name. No one would believe me. I just know in my gut that what happened was wrong. I just feel so guilty.

Has anyone else struggled with these feelings? How do you deal with them?