@Lia33 No problem and good luck! No offense to your sister, but if you want to find out if this is a travel agent that truly knows her stuff, ask if she has an IATA or CLIA number. Those are industry organizations - try to think of it as a Good Housekeeping seal of approval. If she is part of one of those (IATA is better but CLIA is still good) then she'll have access to more.
I'd also ask who she'd be booking your room block through. Two popular tour operators are Travel Impressions and MLT Vacations. Nothing wrong with booking directly with the hotel, but your perks won't be as good. Those are the ones who will help her to get you some good perks.