At what point is too much?

I have a pretty regular period cycle for the most part. Occasionally, aunt flow will through me for a loop and make me wait three or four days to show up. This month, I am working on day 12. I have been taking test every three- four days with no sign so far of a line or period in the near future. I plan on making an appointment with my doctor in the next few days if she has an availability but if not I don’t know how long I’ll have to wait. Is this long enough to be concerned? Or am I over reacting?