*****Worried I might be pregnant....

I had unprotected sex with my bf last month on the 30th but I took the plan b pill a day later just to nake sure I wasnt going to get pregnant. Then we did it again 5 days later but we used protection this time. Now were in a new month and we haven't had sex but when I just not checked my CM (cervical mucus) its brown.. and I looked it up saying im either pregnant or when I was stretching I might have pulled sonething. Im not ready for a kid and im freaking out.... someone with experience... please help =(