Your agent is being negligent by not getting back to you. I recommend booking a separate reservation independently now, and emailing your agent to tell her that you want to cancel the reservation she made for you. I wouldn't listen to any excuses as I can't recommend working with someone who's hard to communicate with for whatever reason. If your agent doesn't respond to that email within a few days to cancel, then I would call/email the travel agency's headquarters.
In general, I recommend avoiding travel agents unless they get you a big discount. As you've seen, they create an obstruction between you and Disney, so you can't just manage your reservation directly when needed (and which isn't that hard- it's easier than dealing with a noncommunicative agent). Especially now, a lot of travel agents and travel agencies are probably going to go out of business, so it's a bad time to have your reservations bound to them.
Aside from all that, do you have your reservation online on My Disney Experience? If so, then you should be able to book dining reservations and FastPasses on your own, regardless of whether or not you booked your resort & tickets through an agent. Agents get no ADR or FP booking advantage. You get to book ADRs at 180 days & FPs at 60 days on your own, too.