am i preg or not???

me and my boyfriend had sex the first time on march 9,2010 an ever since then ma period hasen't come on.we been having sex alot, alot and he hasen't cum inside me but he say's he pre-cums in me all the time.one night he did like 3 times he said but when he actually nuts he take it out an do it somewhere else like on my butt.and one night he nutted on top of me on my vagina and it was alot to.and i went to the bathroom to go whip it off me wit a towel.but ma period hasent come on since march 9 an its april 13 now.sometimes i feel naustious an i be tired alot to and one night i had a sharp pain threw my stomach.i took 3 test an it came up negative i think that was a week later after march 9.ever since then i haven't taken one.but idk what to thank.am i pregnant? am i not? maybe i am if he pre-cums inside me all the time.idk someone tell me,help me out.