I think I might be pregnant

I'm 16 and I had sex with my boyfriend a week ago and didn't use a condom but he didn't cum inside me. My period was supposed to start two days ago and I'm terrified to scare my mom me and my boyfriend are thinking about abortion because we have our whole lives ahead of us. Is there any chance this app could be wrong?! My period is all messed up sometimes I dont get my period for two months so I'm not sure if I am?!