I once had a senior leader in my bureau ask me in a full staff meeting who was looking after my newly born third child after I returned to work. I told him she was in a basket in a closet where she would be safe until I got home. People do make the darnedest assumptions about what's appropriate to ask of moms - don't get me started on strangers asking about breast-feeding plans.
I dig your zeal. I had my first at 26 under similar circumstances to yours. I also want to be in the workplace and I have risen professionally while bearing/raising three kids. My husband works full time and shares parenting duties. (But let me know how you feel about this when you're 40. Because I am militant about our right to be here, but I am also EXHAUSTED.)