I just started back on a ketogenic diet, and I need a little advice.

I need to lose quite a bit of weight (around 40 lbs) by Feb. and I have done just that before (on Atkins). I use MFP, but I was wondering how firm the calorie intake really is. I wanted to know also what type of keto strips to try. Also, my other concern is that once I get to my goal weight, it become difficult for me to stop losing if I stay in ketosis, and I can't lose too much ( I am doing this to try to prepare for a pregnancy). Any maintenence plan suggestions?