My gf took a pregnancy test 6w after rubbing our genitals. she is still virgin. there could be precum. the test came out neg. should i trust this?

Yes: Today's home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, or medications. A correctly done urine test will give a reliable result 3 weeks after sex (or when conception might have happened) or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon.