Welcome and congratulations on your engagement!
Fares and schedules are not available too far in advance. Once the fares come out from the tour operators, you can get a group rate, but not a flight number or departure time (that will be announced later). I cant imaging a TA not wanting to give you a quote.....afterall, they want your $$$
I would consult with more than one TA....just to make sure you get the best price you can get for your guests.
In the meantime, you can book with the wedding coordinator at your resort and send out your STD's....I'm sure there some info on this forum about STD wording.
Good luck!
Alicia