If your partner tested negative for HIV at the time of your encounter, you don't have anything to worry about. If she had a transmissible level of HIV virus, she would have tested positive, so it's extremely unlikely she had HIV.
If you are not able to get over this, take a test at least 42 days after your encounter for peace of mind, but there is really no medical reason for you to test again. You did not get HIV from this encounter, and your 37-day negative test proves this is the case.