i just done a pregnancy test yesterday and it tested positive,,,im extremely happy but im confused about how long i could be,,,,if i had sex 15 to 20 days ago does it mean im pregnant since then or could i have been pregnant before i had this sex from a previous partner as i had no period since september and its now november!!!!!im really worried and any help would be great!!!! could the test really detect a pregnancy,excatly two weeks after sex,,,,please help!!!!!!!!!!!