I would go to the GP asap and ask for antibiotics (erythromycin or clarithromycin are the ones that work) just in case. By the time they diagnose, it's just too late. It's a shame but most gp's are actually quite ignorant when it comes to vaccinations and things like whooping cough. I would NOT take any chances. Since you are at the late stage of preg, chances of infecting bub at birth is high. AB's won't treat whooping cough but make symptoms more bearable and reduces spread of infection. I would get everyone in your family on ab's.
I got whooping cough at 28 weeks and it was SEVERE for 15 weeks! I would not wish that on anyone. Even after going to 2 dr's and 3 visits later (after recommendations from the drug info centre at major hosp), the dr's failed to do anything and only gave me ab's after 5 wks - needless to say it was ineffective at this stage. I got it off a colleague at work. He got ab's asap and the difference in our symptoms were collosal! I suffered for weeks and he just had a mild/moderate cough for a few weeks.
Not trying to scare you or anything - sorry! but there is so little info out there. Good luck, hun