General

I observed that the size I would find ideal on a woman did grow through the years. Even though I was always attracted to women both smaller and larger than my actual "perfect" preference, that ideal did indeed grow steadily.

Are there FAs for whom this didn't happen, who had their preferences as large as they have it now for as long they can remember, or are there even FAs for whom it was the reverse, and they had larger ideals in the past?

For me, many years ago the "perfect" woman's body shape was the smallest which would still be obviously called fat, who could just no longer hide the fact she's overweight. Now it has grown to a size where one starts having to make adjustments to many things in her daily life as activities start emerging she can either no longer do or can only do it in limited ways, and where many things are no longer designed for her size. Still completely independent, but there are obvious adjustments having to be done due to her size.

I wonder if this keeps going on...

Yes, I don't find this implausible to happen to me. I'm not finding women with any significant mobility issues alluring, but I guess if I really was in a relationship with someone at (or growing towards) that size, this might change and my horizons would expand even further.

And as there are still a few (very few) thin or just slightly chubby women whom I can find very attractive, my horizons are really expanding and not just shifting

For me, yes. I noticed the larger girls in school, and I did not dislike them. But I didn't realize that I preferred them until I was in my 20's.

Same here !!

My preference has always been for plumpness, just on the cusp of fat. There's something endearing about it, although I did enjoy fattening my bf a little more after he reached my goal. But where he is now is just the right amount of fat.