I am 18 years old and last month I and my boyfriend just kissed and our bodies were really close to each other. After coming back I noticed a white substance in my underpants. Since then I think that I might be pregnant and that there's a chance. My periods were 4 days late which is normal but this time they were very light and lasted only for 3 days, which has never happened before. I feel like it may be because of stress and anxiety but I am not sure. Is there any possibility that I might be pregnant?