Bizare... Obviously 9 kids is a big family, 6 kids is a big family even if you werent counting the stepkids.
I would love a big family myself, I currently have 3 which is strongly 'normal' I feel but still 'big' to a lot of people.
I would say 1, 2, 3 is very standard (most people I know and most families at my kids school fit into this)
4 is pretty normal too (especially among people who have gone on to have children with a second partner etc... in my experance)
you cross to 5 it could be seen as big depending on circumstances (I mean if you have 3 bio kids and 2 part time step kids it might not 'seem' as big to people a 5 close age bio kids etc... which isnt too unusual)
but by 6 your definately into big catagory regardless.
As for questions how do you fit them into a car or book holiday rooms etc...?
I have 3 (would like 5 or 6 although maybe not likely) and we already struggle to fit them in cars.
Hotels like travelodge are built for 2 adults 2 kids etc... and I wouldnt trust them in another room which doubles the cost too (and would still only be 8 not 9) even caravan holidays etc... usually only sleep 6-8 people.