So impatient!!

We've been ttc for a few months now. I've been really good with keeping up with my cycles and have not had issues in the past conceiving. Well, I'm 3 days late for af and got a bfn on the hpt the first missed day. Afraid to take another hpt because of the dissappointment I felt from the first one. I've always got a bfp when I missed af. What could this mean? Any advice? I'm freaking out.