Pregnant after vasectomy?

My period is 8 days late. I am usually a couple of days late but I have never been this late. Should I worry? I have had a lot of stress in my life and it has never affected my periods. I am not currently stressed anymore than average. I think it is nearly impossible that I could be pregnant (although I wouldn't mind it.) My boyfriend had a vasectomy 3-4 years ago. We have only had twice since my last period and only once that could have been close to ovulation time (10 days into cycle) which I think is too soon to have even been able to conceive. I feel like since my period is off then something must be wrong. The point is should I worry and could there be something going on with my body ... potentially bad? For those of you that suggest going to the doctor I just moved so I can't get into a gyno anytime soon. Thanks.