Had unprotected sex over 5 months ago what do you think?

Ok so in late August I had sex with a girl unprotected, one night stand. Stupid, stupid, stupid, I know. Anyways, it was a one night thing I came inside of her and I questioned her a lot the week it happened and she said not to worry she won't get pregnant, she has an IUD and she got her period supposedly 6 days or so after we had sex. I asked her a month later after the sex and she got very mad at me yelling that she's not pregnant.

So I have cut off all contact with her and haven't talked to her since late September when she got mad and said she wasn't pregnant. I kind of forgot about the whole incident but now fear is back and a lot of things are running through my mind like what if she was lying about having an IUD and she's really pregnant, and then just doesn't want to tell me.

I'm a wreck, I can't even eat or sleep. She has my phone number, so do you think she would have told me if she was pregnant? Should I just move on with my life and assume she is not pregnant?