Hey Amy,
Congrats on the new baby! I can sense that you are so frustrated and I am sorry to hear that. I am no stranger to wanting to lose weight but having no motivation to actually do it.
I think that you should just take it one day at a time. I does take a few weeks for us to develop a new behavior. So I feel that if you can do this more often than not then you are on the right path. You eventually get to the point that its second nature and you don't feel the need to cheat. Little by little and one step at a time. And if your not motivated for yourself, do it because you want to be there for your family for many, many years to come. And if you did it before, there's nothing stopping you from doing it again!I don't know you, but I believe you can do it! Start as soon as you can.
Remember, one day, and one step at a time!