17 and pregnant, please help me?

So, Ive had intercourse on June 6th, then had it unprotected about 2 more times, then on friday i took the Plan B, then had intercourse on saturday morning.. I called planned parenthood and they said that I am not protected from the Plan B that ive taken. My breast are sore and thats uaually a sign of my period, but im not to sure. Im sure that i was supposed to get my period this thursday and i even took a test on wednesday. It came out false but it could have been a false negative. So what do i do, is it possible that i am pregnant ?