What should I do? Pregnant, sick, crazy?

My period is about 8 days late today. I am usually regular and I have never had a period this late...but I am still not having any symptoms that it is coming. I feel confident that I cannot be pregnant (unless it is a miracle.) My boyfriend had a vasectomy between 3 and 4 years ago. I feel like since it hadn't come then something must be wrong with my body. I haven't been abnormally stressed and I have experienced no changes in my life. Should I be worried? I don't have a doctor yet beacuse I just moved.