I'll admit that I'm biased because I'm a TA (I don't work for
Dreams Unlimited but I have used them in the past and had a great experience), but I can't understand why people don't use one. Agents will give you as much or as little hand holding as you want. They'll spend 3 to 5 hours on hold when
free dining comes out changing your reservation. Good agents will answer your emails and calls right away. They'll take care of screw ups when you're in WDW. And most agencies will send you off to Disney with some nice swag--in fact, if you're booking a cruise and not getting an onboard credit from an agent, you should probably find another agent.
You'd be surprised how many Disney reservationists make newbie mistakes that you might not catch. They answer phone call after phone call all day long. They don't know you or have an incentive to keep you happy--if they don't sell to you, the phone will ring immediately after you hang up. For a Disney TA, there's a huge incentive to keep you happy--you might be that TA's only new client that week. So she's going to bust her behind to make sure you get what you need so you come back and you send referrals her way.
Finally, when you book with a TA, you put that money into a small business. When you book directly with Disney, that 10% goes back to the Mouse. And yes, I love the Mouse. But last I looked that 10% wasn't lowering my costs or bringing back Mr. Toad's Wild Ride.
Bottom line, get recommendations, go with an experienced Disney TA (you may be surprised to hear that some AAA agents have never even been to Disney) who goes to the parks frequently (ask--the more they go the better) and by all means, if someone tries to charge you for anything, walk away.
OP, it sounds like the TA you worked with was pretty helpful and you haven't even booked with her yet. Good luck.