In regards to HIV:
1. Does the incident where her vagina rubbed of my unprotected penis through her underwear constitute a HIV risk for me? No.
2. Would her touching my penis with her hands pose a HIV risk considering some of her vaginal fluids may have been present? No.
3. From a medical perspective, given that I had no vaginal or oral intercourse with this woman, is there a need to have a HIV test? Not even a little bit.
In regards to other STDs -
1. Does the incident where her vagina rubbed of my unprotected penis through her underwear constitute a HIV risk for me? If her underwear shifted, this could be a risk for herpes or syphilis.
2. Would her touching my penis with her hands pose a HIV risk considering some of her vaginal fluids may have been present? Hands do not transmit any STDs.
3. From a medical perspective, given that I had no vaginal or oral intercourse with this woman, is there a need to have a HIV test? If you are sure her underwear didn't shift, exposing you to her genitals, then there is no need to test. If you aren't sure, I wouldn't worry too much, and just see your doctor if you get any symptoms, like sores or blisters. (The chances of this happening are slim though.)