Possibly pregnant at 16 and terrified?

So there's is a possibility that I'm pregnant. It is now 8 days after j had sex with a guy I thought I liked. We used a condom and he said he now for sure it did not tear. I asked him if he came and he said I don't know. We didn't do anything before the condom went on and we didn't do anything but kiss with Our clothes on after it came off. I'm not worried about STDs because we are both virgins. I am worried about getting pregnant. They say that condoms are 98% effective when used right but I don't know what that means exactly. I am due for my period tomoro June 30 and I am really stressed out. I have heard being stressed may make your period late. I have no idea what I would do if I'm pregnant let alone how I would tell my parents. It's keeping me up at night and I'm losing sleep over it. PLEASE HELP ME!