Vasectomy question?

So my period since I got it back after our son has been pretty regular not usually more than 3 days late. I am currently on cycle day 42 out of what should be a 34 day cycle. Mine run a little longer. My husband had a vasectomy when I was 7 months pregnant with our son who is now 18 months old so almost 2 years ago. How likely is it that I'm pregnant?