Carly
the 17th is a great date! that's my birthday and have you contacted the wedding coordinator for beaches, her name is Renee Phillips, that is where we were planning to get married originally. Let me know if you want to contact her directly.
Actually if you book through sandals you get the 11th room for free so that's a cool perk.
As for the TA's our host Tammy is a TA and probably can refer you to someone a little more helpful.
A lot of girls on this forum had issues with destinationweddings.com and I don't know that I would trust the mall TA's, which might be part of your frustration.
Have you considered just the two of you going away and then coming home for a really fun reception? If you are set on having a lot of people there, consider a destination that is closer to home for you and your family, which is what I did in changing my plans. My family and friends are all in the west so Nor Cal worked for me and I still am getting a destination wedding, plus a honeymoon in Jamaica. I bet you could still find a great beach location on the East Coast, it might not be an AI but you still have a lot of options.