Pertussis... What are people's experience? How can it be diagnosed early?! My daughter just started…

Pertussis... What are people's experience? How can it be diagnosed early?! My daughter just started to cough and I'm terrified its pertussis. I have a cough and so does our nephew. He doesn't cough a lot but when he does it's a major cough. And when I cough sometimes I have to catch my breath to cough more. I have had two Tdap shots in the past 6 months- a mixed up in my immunization records made me have to get it twice. Once when I was pregnant and then again a couple months ago. Today my daughter woke up with a couch she only coughs a small on me and only a couple times today