ok, i have a realy unsteady cycle,,always ahve,,it comes about every 5 weeks but they can come as close as 3 weeks if the last one was light,,well the last one that i had was like june 7th and lasted for my normal 4 days ,, well a week ago i stayed with my boyfriend ,,he lives in anouther state,,and well the enevidable happened,,,and i should have started any where from about two days ago to not for anouther 3 days,,the thing is it isnt unusual for me to skip sometimes, what im wondering is its been 7 days scince i had sex ,,can sperm live that long so as i get pregnant? and if i skip is that prety much a sure sign im pregnant?

In reguards to your questions you can miss a perood. Some women who have always had regular cycles can skip menses or they can just quit for months all together. It is most likely related to a hormone imbalance and is very common. Sperm can only live in the vagina for a maximum of three days and depending on what day of your cycle you are on depends on if you were even ovulating. I wouldnt be to worried about it if there are no other symptoms, take a test thats the only method to prove one way or another. You can usually get them at the health dept for free. I have worked in the OB/GYN field for years and have seen this happen countless times without a pregnancy occuring.