@procrastinationsupremo
With you all the way!
I am convinced that it's impossible to get slim again after the age of 42-45 y.o. Moreso, if you have been a bit chubby for more than 10 years.
I was 10 and a half stone and a size 12-14, before I had my kids (had them in my late 20's,) and I was only about 11 stone when they were 1 and 2... (I am 5 ft 4.) I was not thin but not fat...
But when they were 5 and 6-ish, I gained half a stone a year until I had gained 4 stone. (So I ended up at around 15 stone, and a size 20 at around the age of 40.)
After hitting 15 stone, I dieted on and off for a decade, and dropped no further down than 12 and a half stone. And the weight always crept back up. I ducked and dived between 13 and 15 and a half stone for 10 years.
I am now 50-ish, and am currently 13 and a half stone. (Last summer I was 15 stone and had been for about 8 months. I dieted and dropped to 13 stone, (by this March!) but I am slowly crawling back up.
)
I literally eat only about 1300 calories a day, I eat less than anyone else I know, and I walk 3 miles at a time, four or five times a week. I also go swimming. Yet for the life of me, I can NOT get under size 16 or under 13 stone.
I don't look awful, but I am not slim. It also upsets me (for some daft reason) that neither of my grown children has ever seen me slim. I have always been fat to them! 
I wish I didn't care but I do.
I have come to the conclusion that I am never ever gonna be below 13 stone again ever. But even so, I do look a lot better at 13 to 13 and a half stone than I do at 15 stone. I look 5 years older than my age at 15 stone, and about 3-4 years younger at 13 stone...
And a 20 to 25 pound weight loss on a 5 ft 4 inch woman is quite a lot really.
I agree that 'just doing your best' is all you can do really.