Late Period

I am now 6, almost 7, days late. I had sex around the 20th and it was protected and I got my period 2 days later and it lasted 4 days but it usually lasts 5. I’m starting to get worried and I think it may be stress. If I don’t get it within the next 3 days I’m gonna take a test. All I know is I’m not ready if it comes back positive. I’m a senior in high school and that would ruin all my plans and my relationship with my mom. If anyone has any advice or any similar experience please let me know(: