Postmenopausal women who struggle with weight

I am looking for other ladies my age to exchange experiences. I am 69.
I never had a huge weight problem in my life. When I was younger and I put on a few pounds too many all I had to do was diet a few days and I was okay again. I was never overweight.
Not so since I went through menopause. I am 5'4 and at one time I was over 150 pounds and from then on I was constantly yoyoing. I went down to 110 and up again in the 140s, down to 120 up again 20 pounds and so on and so on.
I am very active and since I am retired I took up road biking. So every day weather permitting I am out there cycling for hours. I also garden, swim, do Yoga and like to hike.
But I have not figured out a diet which works for me at my age. I seem to need very few calories to survive. But of course 1000 calories a day is not very satisfying and easily surpassed. I am not a big meat eater and I thought that by eating mostly fruits, nuts, eggs and yogurt I would be fine. but I put on weight with that. I already figured out that I have an addiction to bread and cakes and try to stay away from it, which is very difficult for me because I really enjoy good bread and home made cakes.
I went on Atkins a few times which initially works but after a few days I am so tired of meat and fat that I rather do not eat at all, which leaves me too sluggish to move.
That whole postmenopausal thing is not working for me. I finally found some supplement "Remifemin" which seems to help with the hot flashes, but I still suffer from insomnia and mood swings.
The constant yoyoing has left my skin saggy and so when my weight is down I get so depressed about the saggy skin that I eat again to fill out. But my general well being and energy level is best when I am around 115 pounds. So anybody out there who has found the stone of wisdom? I do not want to exclude the rest of the population , but it is really a problem of women of a certain age.......