Calm down. Your risk is low. Here are the facts:
1. She probably is not infected. The description you gave is not of a particularly high risk person. If she is not an IV drug user and if her partner did not have sex with other men, her likelihood of having HIV is far less than 1%.
2. When she told you she had nothing she was probably telling the truth. Most people do,
3. Even if she was infected your risk from unprotected sex is only about 1 in 1000 acts of intercourse, again moving the odds in your favor
Putting all of this together, your risk is low. Should you get tested - yes. As "screening", not because you are at any huge amount of risk. You describe unprotected sex. we would suggest that anyone with unprotected sex with a new or multiple partners qualifies for periodic STD/HIV "screening (testing in the absence of symptoms) . As a matter of personal protection, we recommend annual testing for anyone who has had either a new or two or more sex partners in the past year (we consider this to be health maintenance- we also recommend you get your blood pressure and cholesterol checked regularly).
Hope this helps. Don't worry. I predict your tests will be negative. EWH