3 days late, help

Okay I'm 3 days late and I have a regular period that is only 4-5 days long. My period came last month but not this month. I haven't been stressing at all so it should be on time. Usually if I am late it's only one day. But if anything I'm usually early a day. My boyfriend and I haven't had sex since August 12 and that was 3 days before my fertile days. I'm planning on taking a pregnancy test tonight since i didn't start last night. I scared I might be pregnant..