J.A.
I have had controlling in laws and I am married to their oldest so we were the first to do everything, get married, buy a house, have kids etc. Nothing was easy and I noticed that when his brothers went to do things, they were less and less critical. We were paving the way for the others.
It is never an easy situation when parents are this way, however, the most important thing is that you are doing what you desire for your life, your marriage and your growing family. There are only two people in the room when a child is conceived and it is those two people who matter most.
There is a book called "If you had controlling parents" that might be worth a read. My husband and I at one point really took a step back from his family and slowly reintroduced ourselves back into their lives, this time with healthier boundaries. It was hard and a lengthy process, however, we have a better relationship and there is no more interference in our marriage or undermining our parenting.
Someone advised me once to simply say "Thanks for your input, I'll keep it in mind" whenever anyone gave unsolicited advice, criticism etc. Then go do what you know is best for your lives.
Good luck and I am sorry you are dealing with this. It sounds like you have a wonderful family and want to enjoy your parenting time. I applaud you!
J.