OK, I'll admit it. I'm a nervous parront. Chula is starting to drop feathers. So far this evening, I count somewhere between 6 and 10 of differing sizes. She is 4 months and 1 week old. Is that about the right age for a first molt? I ask because she has been preening under her chin more than usual. I'm not thinking that she is plucking, but how do I tell the difference?

Probably molting.

Thats just about the age that most babies start molting and acquiring their adult plummage.

Usually if you have a plucker they will pluck one spot till there is an actual bald spot. You'll be able to see skin easily. Molting will be as you've described different sized feathers but you won't see any bare spots, You'll soon be seeing pin feathers...which is a feather that has a hard sheath over it that resembles the end of a shoe string. The bird will need your help preening those off the back of his neck and head because he can't reach those areas on his own...its a great time to do some bonding. Be careful though as you pinch the pin between your thumb and finger as some of them will still have a blood supply and will be tender. Just do a few at a time and talk in a nice comforting voice as you do it.

You might notice that he's a little on the cranky side at times because they get a little uncomfortable with those pins pushing through the skin. They also might be a little more itchy so more baths, showers, or misting will help.

I pretty much thought it was a first molt, but the problem is that I have not seen hardly any quills, and the feather droppage is getting heavier. These seem to just be falling off when she shakes, preens and/or we pet her.

The fact that they seem to be just falling out is a good thing. =) Pluckers forcefully TEAR the feathers out. If the feather really isn't ready to come out you can actually hear the bird squeaking in pain every feather they pluck. Those new ones take a bit to grow out and depending on how big the feather is they're REALLY hard to miss in the rest of the feathers. If you're keeping an eye on her than you're doing the right thing so try not to worry too much about it.