Pregnancy, preg. tests, and periods

Ok I had an earlier question about this. My girlfriend had a wet spot on her jeans around her hip after dry sex. We found the wet spot and she switched pants like 2 mins after that. Just for sure she wanted me to get a pregnancy test for sure. She took one 4 days after her missed period, and the other a week after her missed period. Both of them said negative. The signs are looking like she isn't pregnant but still. What is up with her period? If you can give me any answers/advice on that stuff it would be great.

Thanks

Well, pregnancy tests are VERY accurate, and 2 can almost guarantee accuracy. depending on how old your friend is, her periods may still be irregular, as is comon in adolesence. Your periods can also be affected by a change in diet and excercise, or even stress. If you are still unsure, you could go and see a doctor. You may want to see one just to figure out why your periods are irregular.