hypothyroid, post-menopausal and stuck on a plateau with Atkins

I am about as frustrated as you can get now. I know that others have been through this and need some support. I started the NEW ATKINS, after reading the book in its entirety, June 27 of 2011. ( I had been successful on Atkins for years, the old one, until I got kidney stones for not drinking enough water.)I have lost 45 lbs, most of it in the early stages of the diet. I stayed on induction longer than listed and eventually moved to the OWL phase, adding strawberries or raspberries, carefully measured, as my addition. I slowed down to a pound a month weight loss. Then finally, a month ago, I dropped some weight- not a lot, but enough to post a 2 or 3 lb loss. Since then I have gained weight. I have been up and down, up and down. I have cut back on some protein. I have cut back on salty foods- since my body reacts very quickly to them.
I write EVERYTHING that goes in my mouth down in my food and fitness journal.
I drink my water.
I joined a gym over a month ago and work with a trainer at least three times a week and try to get in another workout or two on my own.
I watch the amount of protein I eat so as not to go overboard.
I have gotten through every holiday and celebration without cheating.
I rarely if ever indulge in a glass of white wine.
So what else am I supposed to do. When I look back at my diaries- I am on the fourth one now. I have only lost 6 lbs since Christmas. All of that loss ended a month ago.

Maybe you aren't getting enough fat? Maybe you should add a tbsp. of coconut oil or some other healthy fat.