
Hopefully it will subside within the next 3 or 4 weeks so you can get her done this time.
If you think about it if she was in season 12 weeks ago, had she been mated her litter would be about a week old,s o she is at the right stage to have milk.
It might be worth cutting her protein down, by giving her a senior food for example, and increase the exercise (when it is cool) and remove her bedding and her bed even, as this harsh regime tends to make their bodies forget about being Mums.
I would discourage her from licking her teats as this will stimulate them. A Polo shirt put on back to front will be useful and you can pin any excess to keep her from licking.