Well, I'm going out on a limb here and saying that the answers you are looking for are right in front of you.
You provided them in your post !
As with so many things in life, timing is everything.
A new Mom with a 3 yr old and another one on the way is generally not going to have sharing her hubby and all the complexities that go with that very high on her priority list !
She's probably overwhelmed somewhat as it is, hormonal, confused, tired etc.
Be patient. Try to keep a conversation going, keep learning together, but DON'T push activity or timeframes. Be there for her to help her handle what she has on her plate already. All things can come in their proper time and will fit better when that timing is right !