am I pregnant??

me and my boyfriend had unprotected sex, I had bleeding after 6 days and I had brown discharge a while after. I took a pregnancy test 1 week after I had sex and it came out negative. Now my period is 18 days late & I have a doctors appointment on the 23rd of June FOR BIRTH CONTROL ... my mom doesn't know I started having sex & she wanted me to be protected. I'm only 14 so if I'm pregnant how do I tell her?