well, if I healthy weight loss is 2-3lb a week. And we say its 12 - 15 weeks. Then I guess it would be between 36 - 45lb. I guess i depends what diet you are on to what you actually loose as well as your age, and body type that sort of thing.
I would not worry to much about the numbers, I would get my head around living a healthy life style. The weight will come off then. and also that is good expearance and habit forming behaviour for keeping it off.
Are you trying to loose weight for something happening in 3 months? I did that for my birthday, I wanted to loose loads before I turned 30. It can be done
I am on a break from trying for a baby after nearly 2 years trying I successfully fell pregnant last month but then had an early miscarriage and the doctor implied it was my weight
So 3 months out to lose as much weight as possible then back to trying
I'm gonna give paul Mckennas hypnotic gastric band a go I've heard good things about it.
I really wish you the best with this! It's so different for everyone no one could say. I hope you lose the weight fast and in a healthy way and good luck with the baby making