can your employer ask you what your plans are post pregnancy. I told my company at 4 months that I was pregnant and told them I would let them know my plans as it got closer. They approached me at 6 months and asked if I was coming back or not. Can they do that?

Sure, they can ask, and why wouldn't they? They are looking to see if they are going to need to replace you permanently or not. Will your absence be covered under FMLA?

Yes they can ask, particularly when you said you would let them know your plans at a later date. They don't have to guess when you will make up your mind. They are permitted to ask.