Thank you all for your responses. This is such a weird year for this little pet birdie!
Our parrotlet is now 12 (I looked it up). Since she was 9, every June, she'd lay one to three eggs, quit and be done. I attributed her egg cycle to the outdoor bird cycle - every mid-May and early-June, she's in her cage sitting in the garden with me as I plant and weed and get the garden established. (She has a 'travel' cage which she is in and follows me around the house - her 'flight cage' is in her owner's bedroom (oldest son away at school)).
She usually doesn't molt this season, typically molts begin about October for her.
Yes, she has cuttlebone, and I added some smaller pieces of oyster shell into her feed for extra calcium.
This season has been particularly weird - she's now on egg #12! Eggs 10 and 12 were the first to be solid enough to stay whole. The others were more of a thin-shell/membrane only type eggshell...and they were crushed when she laid them - she preferred to lay from the topmost perch in her cage, so they had quite a ways to travel to the bottom of the cage! These two survivor eggs were laid on the floor of her cage.
She is acting broody - she has the brightest green feathers I've ever seen on her - she's plucked part of her chest feathers from neck to vent - but she's guarding the eggs, not sitting on them. She's in her flight cage, and refuses to come out to her daytime cage...which is ok with me. I check on her periodically through the day, but she just does her 'I'm a pissed off broodie birdie - go away!' act, so I leave her be.
She's laying behind the eggs and 'guarding' them. I've left these two eggs with her, and she nudges them (but not towards her, just sort of rolls them around), she's eating and drinking as usual.
It's now been 3days with these two eggs...and I'm hoping she'll give up soon. But I believe she's in decent health despite the extra calcium lost...input and output seem fine.
I know she'll eventually give up. Any clue when?