I am 16 years old and had unprotected sex 12 days ago, 2 days after that I thought I had come on my period however it only lasted 2/3 days and my periods usually last 4/5 days, the bleeding was quite heavy to start with however towards the end became lighter. I took a pregnancy test 3 days ago and it came back negative, I was quite relieved however I am still worried because I may have taken the test too early. When would you recommend taking the test for the most accurate results. I believe I am pregnant because of the bleeding, my lower back hurts, I am very emotional and keep having mood swings. My nose is constantly running even though I don't have a cold and whenever I think about being pregnant my belly feels weird, its like butterflies? I have never experianced anything like this before. (My periods are never on time, they are very very irregular so I do not know when I was supposed to come on my period)