Your supplements are way off. She needs calcium without d3 every feeding, calcium with d3 twice a month and a multi vit twice a month.
Reducing her calcium will not prevent her making eggs. It will damage her, as she will take whatever calcium she can get to make those eggs, leaving her bones at serious risk of mbd, along with other problems ,ie, being able to lay etc etc.
Some people have success with reducing egg laying/making by reducing the amount of food and lowering the basking temp.
I'm sure someone with a bit more knowledge and experience will be able to clarify this and give you more help.
With regards reducing the food, that would, I guess, depend on the age. As she is only 6 months, this may not be an option just yet. As she's still growing and needs the food.
Hope she can turn around and get better.
A picture may help members too, kath.