As for getting a pap once every 2 years, that was in vogue for a very short time and is medically incorrect.

As for every 6 months, the only time I know of that 6 months would be appropriate is if you're young (teenagers being notoriously "not quite accurate"m with their history... they have multiple partners, or their one partner has multiple partners so they are at very high risk for STDs and should be checked every six months) or if you are not in a monogamous relationship. Remember you have to multiply the number of partners you have with the number of partners he has
Definitely feel perfectly comfortable to ask him straight out. Don't chicken out and ask the receptionist. Ask him/her