Well, time for an update.
we've had some rough times and the lady hasn't eaten too much. She's now 195 lbs and I plan to keep her around that. It's under 200, her mental barrier. Meanwhile thanks to the ballooning she has a wonderful fat skirt she can't get rid of, so even at her lower weight she has a nice fat profile. Good round belly; you wouldn't mistake her for a thin person. When she lays on her side it blobs around nicely.
When she gets too thin in the face, or her neck or double chin is not pronounced enough, I usually put her on a butter diet. Double butter on toast, and every meal has butter added to her portion. About 1 lbs of butter in a week.
Obviously I'm not that into everything at the moment, but I like to keep her looking and feeling fat. With a bit of the weight loss she feels softer, more blubbery. Her fat skirt has a wonderful "I'm fat" effect on her, something I encourage and compliment her on of course. Still grab it often from behind, weighing it in my hands, and letting her know how nice it is.