The answer to your last question is that if such low risk events -- frottage, hand-genital contact etc, could transmit HIV
, then don't you agree that in the 30+ year worldwide HIV
epidemic, there would be at least one case in which such exposure was the only potential source of infection? Yet there are none.
So none of your concerns have any basis either in science or in practical clinic policy. Don't get retested, and definitely stop worrying about any of this.