My Girlfriend is telling me shes scared of being pregnant, i need some clarification?

ok so recently my girlfriend has been scared of being pregnant and when i asked why she told me her friend had told her that when when u discharge bodily fluids a few hours after is can be a sign... heres the thing.. we have only had protected and i still pull out while wearing a condom and i have never had a condom break on me...im very paranoid and do the water test every time after (weird i know but i like to be safe)... can some body explain what is going on so i can make clear of the situation? i did research but i didnt find anything that directly helped me