Re: 17 months and still going but...
Repeat after me: "The American Academy of Pediatrics says that 'Increased duration of breastfeeding confers significant health and developmental benefits for the child and the mother,' and that 'There is no upper limit to the duration of breastfeeding and no evidence of psychologic or developmental harm from breastfeeding into the third year of life or longer'." (Reference: http://aappolicy.aappublications.org...rics;115/2/496)
It's totally normal for a baby to calm rapidly in response to nursing. It's one way in which breastfeeding makes life easier on a mom, as opposed to a dad. All those months when you've been up at night with the baby and he hasn't- the fact that you can calm her more easily now is your payback for that! Your DH needs to stop blaming nursing for his difficulties in calming her, and develop some alternate ways of soothing. It's going to take some creativity on his part, but that's parenting for you. Suck it up, buttercup!
If you can't establish boundaries, the only thing you can do is ignore her. Or perhaps have a huge blow-up. Sometimes a screaming fight is what it takes...
As for the mother-in-law, any advice to establish boundaries are moot, she is loving but terribly intrusive and have not won that battle and likely never will.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"